Hitachi VSP G1000, VSP G200, VSP G1500, VSP G600, VSP F1500 User Manual

Hitachi Thin Image

User Guide

Hitachi Virtual Storage Platform G1000 and G1500

Hitachi Virtual Storage Platform F1500

Hitachi Virtual Storage Platform G200, G400, G600, G800

Hitachi Virtual Storage Platform F400, F600, F800

MK-92RD8011-12

June 2017

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2

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Contents

Preface................................................................................................. 9

Intended audience................................................................................................. 10

Product version......................................................................................................10

Release notes........................................................................................................ 10

Changes in this revision..........................................................................................10

Related documents.................................................................................................10

Document conventions........................................................................................... 11

Conventions for storage capacity values................................................................... 13

Accessing product documentation........................................................................... 14

Getting help...........................................................................................................14

Comments.............................................................................................................14

1 Overview of Thin Image.......................................................................15

About Thin Image.................................................................................................. 16

Workflow for storing Thin Image snapshot data..................................................17

Components of Thin Image.....................................................................................18

Thin Image pairs.............................................................................................. 18

Volume components..........................................................................................19

Snapshot tree components ...............................................................................20

Consistency and snapshot groups...................................................................... 20

Snapshot Clones ..............................................................................................21

Snapshot trees and cascaded pairs ................................................................... 22

Creating cascaded pairs.................................................................................... 22

VSP family software applications for Thin Image................................................. 25

How Thin Image works...........................................................................................26

How Thin Image uses pools and pool volumes....................................................26

Usage level rebalancing among parity groups..................................................... 27

How Thin Image uses V-VOLs............................................................................28

How Thin Image pairs are created..................................................................... 29

Using snapshot pairs (not cascaded) ................................................................. 29

Using cascaded pairs.........................................................................................30

Workflow for creating groups and storing snapshot data using CCI.......................33

Methods of storing snapshot data...................................................................... 35

Thin Image pair restoration............................................................................... 37

How Thin Image pair status changes.......................................................................37

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

3

Thin Image host access and pair status..............................................................39

Workflow for Thin Image pair status changes..................................................... 40

Copy threshold option and host server I/O performance for Thin Image.....................41

Sharing Thin Image volumes with other software applications................................... 42

Sharing Thin Image volumes that have Data Retention Utility access attributes..... 44

Sharing Thin Image volumes with Hitachi Volume Migration.................................47

Sharing Thin Image volumes with ShadowImage................................................ 47

Sharing Thin Image volumes with TrueCopy and Universal Replicator................... 49

Volume backup with Thin Image, TrueCopy, and Universal Replicator in a 3DC

multitarget configuration workflow............................................................... 51

Volume backup with Thin Image and Universal Replicator in a 3DC multitarget

configuration workflow (VSP G1000, G1500, and VSP F1500)......................... 52

Volume backup with Thin Image and Universal Replicator in a 3DC cascade

configuration workflow (VSP G1000, G1500, and VSP F1500)......................... 52

Sharing Thin Image volumes with global-active device........................................ 53

Storage system configuration with Thin Image and GAD................................ 54

Consistency group configuration with Thin Image and GAD............................58

Snapshot group configuration with Thin Image and GAD................................60

Sharing Thin Image volumes with Dynamic Provisioning and Dynamic Provisioning

for Mainframe in a single storage system............................................................62

Sharing Thin Image volumes with Resource Partition Manager............................. 63

System option modes for Thin Image...................................................................... 63

Acronyms and abbreviations for VSP family storage system software applications used

in this guide...........................................................................................................66

2 Thin Image system and planning requirements...................................... 67

Thin Image system requirements............................................................................ 68

Installing Thin Image........................................................................................68

Uninstalling Thin Image.................................................................................... 68

Thin Image licensed capacity requirements.........................................................68

Thin Image shared memory requirements.......................................................... 69

Thin Image volume requirements.......................................................................70

Thin Image data pool requirements................................................................... 73

Thin Image consistency group requirements.......................................................74

Thin Image snapshot group requirements.......................................................... 75

Thin Image planning requirements.......................................................................... 76

Calculating the number of Thin Image pairs based on pair tables......................... 76

Calculating Thin Image pairs based on the snapshot estimated manageable capacity

.......................................................................................................................76

Calculating Thin Image pairs based on cache management devices......................77

Calculating the number of cache management devices........................................ 77

Calculating the Thin Image pair capacity for DP pools..........................................78

Thin Image cache management device requirements.......................................... 80

Calculating and assigning pool capacity.............................................................. 80

Resolving insufficient pool capacity...............................................................81

Pool capacity calculations.............................................................................82

Creating a backup of data............................................................................82

Universal Volume Manager and external volumes used as pool-VOLs.................... 82

Simultaneous processing of multiple Thin Image pair tasks..................................83

Pair operations when pairs are cascaded ........................................................... 83

Pair operations when pairs are not cascaded.......................................................94

4

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Pair operations when a P-VOL is shared by multiple S-VOLs................................. 95

Differences between Thin Image and ShadowImage........................................... 96

3 Configuring Thin Image........................................................................99

Prerequisites for configuring Thin Image................................................................100

Workflow for configuring Thin Image..................................................................... 100

Workflow for creating and managing Thin Image pairs...................................... 101

Creating Thin Image data pools....................................................................... 101

Selecting pool volumes....................................................................................104

Pool creation and data drive type priority..........................................................106

Workflow for registering virtual volumes.................................................................107

Editing the SSID for virtual volumes (VSP G1000, G1500, and VSP F1500).......... 107

Changing V-VOL settings................................................................................. 110

Creating V-VOLs for Thin Image S-VOLs........................................................... 113

Removing LDEVs from registering tasks...................................................... 117

Recognizing devices from the host server....................................................119

Host server stoppages and device recognition issues....................................120

Overview of using CCI to run commands through in-band connections.....................120

Changing system options that affect Thin Image performance.................................121

4 Managing Thin Image Pairs.................................................................125

Thin Image pair tasks...........................................................................................127

Checking Thin Image pair status........................................................................... 127

Reloading Thin Image configuration information..................................................... 128

Workflow for creating and managing Thin Image pairs............................................128

Workflow for creating Thin Image pairs using Device Manager - Storage Navigator... 129

Creating Thin Image pairs using Device Manager - Storage Navigator...................... 130

Selecting a pool as your primary volume...........................................................133

Example of creating complex Thin Image pairs.......................................................133

Creating Thin Image pairs and defining them in snapshot or consistency groups using

CCI..................................................................................................................... 134

Workflow for defining Thin Image pairs and defining them in snapshot or consistency

groups using Device Manager - Storage Navigator.................................................. 135

Storing snapshot data or cloning pairs................................................................... 135

Splitting Thin Image pairs to store snapshot data................................................... 136

Splitting Thin Image pairs to store snapshot data using CCI...............................137

Workflow for storing snapshot data or clone pairs in consistency groups.................. 137

Using consistency group pair-split with shared volumes..................................... 138

Restoring Thin Image pairs................................................................................... 141

Failure during Thin Image pair restore..............................................................142

Restoring suspended Thin Image pairs............................................................. 143

Thin Image pair resynchronization.........................................................................143

Pair resynchronization methods........................................................................143

Resynchronizing Thin Image pairs....................................................................144

Assigning MU numbers to deleted snapshot data.................................................... 145

Deleting snapshot data......................................................................................... 145

Deleting Thin Image pairs.....................................................................................146

Accelerating the Thin Image pair deletion process.............................................148

Removing Thin Image snapshot groups............................................................148

Assigning secondary volumes to Thin Image pair snapshot data.............................. 148

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

5

Assigning secondary volumes to snapshot data after creating new Thin Image pairs

..................................................................................................................... 149

Assigning secondary volumes to snapshot data of existing Thin Image pairs....... 151

Releasing assignment of secondary volumes from Thin Image pair snapshot data.....152

Changing assignment of secondary volumes to Thin Image pair snapshot data.........153

5 Monitoring and maintaining Thin Image...............................................155

Monitoring pair information................................................................................... 156

Viewing summary replication information..........................................................156

Viewing local replication summary information.................................................. 157

Viewing the number of pairs............................................................................ 158

Viewing the list of primary volumes..................................................................159

Viewing pair properties ...................................................................................160

Thin Image pair status definitions.................................................................... 160

Viewing pair synchronization rates................................................................... 161

Monitoring consistency groups.............................................................................. 163

Viewing the number of consistency groups....................................................... 163

Viewing the list of consistency groups.............................................................. 164

Viewing consistency group properties...............................................................165

Viewing Thin Image pair task history..................................................................... 167

Thin Image task code definitions......................................................................168

Viewing licensed capacities................................................................................... 169

Viewing the number of cache management devices................................................ 170

Managing pools....................................................................................................170

Monitoring pool information.............................................................................170

Viewing used pool capacity (VSP G1000, G1500, and VSP F1500).......................172

Viewing used capacity by pool....................................................................172

Viewing used capacity of the physical capacity by pool.................................172

Viewing used pool capacity by Thin Image pair's root volume....................... 172

Viewing formatted pool capacity and pool usage rates.......................................173

Increasing pool capacity..................................................................................173

Failure of available pool capacity formatting and pool capacity increase......... 177

Decreasing pool capacity................................................................................. 177

Stopping the process of decreasing pool capacity.........................................179

Editing the data pool warning threshold............................................................181

Editing pool names......................................................................................... 183

Workflow for recovering blocked pools..............................................................185

Recovering blocked pools...........................................................................186

Workflow for deleting pools............................................................................. 187

Deleting pools........................................................................................... 187

Managing virtual volumes..................................................................................... 188

Editing virtual volume names........................................................................... 188

Workflow for deleting V-VOLs specified for Thin Image S-VOLs...........................191

Deleting virtual volumes.............................................................................191

Viewing snapshot data capacity (VSP G1000, G1500, and VSP F1500)......................192

Maintaining pairs during storage system maintenance.............................................193

Switching off the power supply........................................................................ 193

Power supply and existing shared memory..................................................194

Power supply and losing data in shared memory..........................................194

Replacing the microcode (or firmware) offline................................................... 194

Definition of failure...............................................................................................195

6

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

6 Troubleshooting Thin Image............................................................... 197

Troubleshooting pools, pairs, and volumes related to Thin Image.............................198

Workflow for correcting pool-related failures (SIM = 601xxx, 602xxx, 604xxx,

605xxx, and 606xxx).......................................................................................200

Workflow to perform when SIMs related to the pool usage rate were reported

................................................................................................................201

Workflow to perform when SIMs related to the capacity ensured for writing were

reported .................................................................................................. 204

Workflow for fixing errors when SIMs related to cache management devices are

reported.............................................................................................................. 206

Calculating the number of remaining cache management devices.......................207

Workflow for fixing errors when pool-related SIMs are reported............................... 207

Completing SIMs (VSP G1000, G1500, and VSP F1500) ..........................................209

Automatic completion of SIMs .........................................................................209

Manually completing SIMs............................................................................... 209

Contacting customer support.................................................................................210

A CCI command reference for Thin Image.............................................. 211

Pair tasks using CCI or Device Manager - Storage Navigator....................................212

CCI pair command results..................................................................................... 213

Troubleshooting with Command Control Interface...................................................213

Command Control Interface SSB2 codes...........................................................214

Notes on using Thin Image primary volumes as TrueCopy, ShadowImage, or

Universal Replicator pair volumes.....................................................................222

Notes on storing snapshot data, and on cloning pairs ..................................223

B Thin Image GUI windows and wizards................................................. 225

Replication window...............................................................................................226

Local Replication window...................................................................................... 228

View Pair Synchronization Rate window..................................................................239

View Pair Properties window................................................................................. 242

History window.................................................................................................... 247

Consistency Group Properties window....................................................................248

Create TI Pairs wizard...........................................................................................251

Create TI Pairs window................................................................................... 251

Assign Secondary Volumes window.................................................................. 258

Create TI Pairs confirmation window................................................................ 263

Select Pool window...............................................................................................267

Split Pairs wizard..................................................................................................269

Split Pairs window...........................................................................................269

Split Pairs confirmation window........................................................................271

Resync Pairs wizard..............................................................................................273

Resync Pairs window.......................................................................................273

Resync Pairs confirmation window....................................................................275

Delete Pairs window............................................................................................. 277

Edit Local Replica Options wizard...........................................................................279

Edit Local Replica Options window................................................................... 279

Edit Local Replica Options confirmation window................................................ 283

TI Pairs window................................................................................................... 285

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

7

Assign Secondary Volumes wizard......................................................................... 288

Assign Secondary Volumes window.................................................................. 289

Assign Secondary Volumes confirmation window...............................................293

Remove Secondary Volumes window..................................................................... 296

Glossary............................................................................................ 299

Index................................................................................................ 321

8

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Preface

This document describes and provides instructions for using Hitachi Thin
Image to plan, configure, and perform pair tasks on your storage system.

Please read this document carefully to understand how to use this product,
and maintain a copy for reference purposes.

Intended audience

□

Product version

□

Release notes

□

Changes in this revision

□

Related documents

□

Document conventions

□

Conventions for storage capacity values

□

Accessing product documentation

□

Getting help

□

Comments

□

Preface 9

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Intended audience

This document is intended for system administrators, Hitachi Data Systems
representatives, and authorized service providers who install, configure, and
operate the storage system.

Readers of this document should be familiar with the following:

• Data processing and RAID storage systems and their basic functions.

• The Hitachi Virtual Storage Platform storage system and the Hardware
Guide for your storage system model.

• The Device Manager - Storage Navigator software and the System
Administrator Guide for your storage system model.

• Hitachi Dynamic Provisioning, Hitachi Dynamic Tiering, Hitachi LUN
Manager, Hitachi LUN Expansion, Hitachi Virtual LVI, Hitachi Virtual LUN,
and Hitachi Data Retention Utility.

Product version

This document revision applies to the following microcode or firmware:

• VSP G1000, G1500, and VSP F1500: microcode 80-05-4x or later

• VSP G200, G400, G600, G800, VSP F400, F600, F800: firmware 83-04-4x
or later

• SVOS 7.2 or later

Release notes

Read the release notes before installing and using this product. They may
contain requirements or restrictions that are not fully described in this
document or updates or corrections to this document. Release notes are
available on Hitachi Data Systems Support Connect:

knowledge.hds.com/Documents.

Changes in this revision

Expanded enhancements for DP pools, which include the ability to set the
maximum reserved V-VOL capacity against the pool capacity, when creating a
DP pool.

Related documents

Hitachi Virtual Storage Platform Gx00 and Fx00 documents

• Product Overview, MK-94HM8013

https://

10 Preface

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

• Hitachi Virtual Storage Platform G200 Hardware Reference Guide,
MK-94HM8020

• Hitachi Virtual Storage Platform G400, G600 Hardware Reference Guide,
MK-94HM8022

• Hitachi Virtual Storage Platform G800 Hardware Reference Guide,
MK-94HM8026

• Hitachi Virtual Storage Platform F400, F600 Hardware Reference Guide,
MK-94HM8045

• Hitachi Virtual Storage Platform F800 Hardware Reference Guide,
MK-94HM8046

• Provisioning Guide, MK-94HM8014

• Hitachi SNMP Agent User Guide, MK-94HM8015

• System Administrator Guide, MK-94HM8016

Hitachi Virtual Storage Platform G1000 and G1500, and VSP F1500
documents

• Product Overview, MK-92RD8051

• Hardware Guide for Hitachi Virtual Storage Platform G1000, G1500, and
F1500, MK-92RD8007

• Hitachi Compatible FlashCopy/FlashCopy SE User Guide, MK-92RD8010

• Performance Guide, MK-92RD8012

• Provisioning Guide for Open Systems, MK-92RD8014

• Hitachi SNMP Agent User Guide, MK-92RD8015

• System Administrator Guide, MK-92RD8016

• Hitachi TrueCopy® for Mainframe User Guide, MK-92RD8018

• Hitachi TrueCopy® User Guide, MK-92RD8019

• Hitachi ShadowImage® for Mainframe User Guide, MK-92RD8020

• Hitachi ShadowImage® User Guide, MK-92RD8021

• Hitachi Universal Replicator for Mainframe User Guide, MK-92RD8022

• Hitachi Universal Replicator User Guide, MK-92RD8023

• Hitachi Universal Volume Manager User Guide, MK-92RD8024

• Global-Active Device User Guide, MK-92RD8072

Document conventions

This document uses the following terminology conventions:

Convention

VSP G series

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Description

Refers to the following storage systems:

• Hitachi Virtual Storage Platform G1000 and G1500

• Hitachi Virtual Storage Platform G200

• Hitachi Virtual Storage Platform G400

• Hitachi Virtual Storage Platform G600

• Hitachi Virtual Storage Platform G800

Preface 11

Convention Description

VSP F series

VSP Gx00 models Refers to all of the following models, unless otherwise noted.

VSP Fx00 models Refers to all of the following models, unless otherwise noted.

Refers to the following storage systems:

• Hitachi Virtual Storage Platform F1500

• Hitachi Virtual Storage Platform F400

• Hitachi Virtual Storage Platform F600

• Hitachi Virtual Storage Platform F800

• Hitachi Virtual Storage Platform G200

• Hitachi Virtual Storage Platform G400

• Hitachi Virtual Storage Platform G600

• Hitachi Virtual Storage Platform G800

• Hitachi Virtual Storage Platform F400

• Hitachi Virtual Storage Platform F600

• Hitachi Virtual Storage Platform F800

This document uses the following typographic conventions:

Convention

Bold

Italic

• Indicates text in a window, including window titles, menus, menu options,
buttons, fields, and labels. Example:
Click OK.

• Indicates emphasized words in list items.

• Indicates a document title or emphasized words in text.

• Indicates a variable, which is a placeholder for actual text provided by the
user or for output by the system. Example:

Description

pairdisplay -g group

(For exceptions to this convention for variables, see the entry for angle
brackets.)

Monospace

< > angle brackets Indicates variables in the following scenarios:

[ ] square brackets Indicates optional values. Example: [ a | b ] indicates that you can choose a,

{ } braces Indicates required or expected values. Example: { a | b } indicates that you

| vertical bar Indicates that you have a choice between two or more options or arguments.

Indicates text that is displayed on screen or entered by the user. Example:

pairdisplay -g oradb

• Variables are not clearly separated from the surrounding text or from
other variables. Example:

Status-<report-name><file-version>.csv

• Variables in headings.

b, or nothing.

must choose either a or b.

Examples:

[ a | b ] indicates that you can choose a, b, or nothing.

{ a | b } indicates that you must choose either a or b.

This document uses the following icons to draw attention to information:

12 Preface

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Icon Label Description

Note Calls attention to important or additional information.

Tip Provides helpful information, guidelines, or suggestions for performing

tasks more effectively.

Caution Warns the user of adverse conditions and/or consequences (for

example, disruptive operations, data loss, or a system crash).

WARNING Warns the user of a hazardous situation which, if not avoided, could

result in death or serious injury.

Conventions for storage capacity values

Physical storage capacity values (for example, disk drive capacity) are
calculated based on the following values:

Physical capacity unit

1 kilobyte (KB) 1,000 (10 3) bytes

1 megabyte (MB) 1,000 KB or 1,0002 bytes

1 gigabyte (GB) 1,000 MB or 1,0003 bytes

1 terabyte (TB) 1,000 GB or 1,0004 bytes

1 petabyte (PB) 1,000 TB or 1,0005 bytes

1 exabyte (EB) 1,000 PB or 1,0006 bytes

Value

Logical capacity values (for example, logical device capacity, cache memory
capacity) are calculated based on the following values:

Logical capacity unit

1 block 512 bytes

1 cylinder Mainframe: 870 KB

Open-systems:

• OPEN-V: 960 KB

• Others: 720 KB

1 KB 1,024 (210) bytes

1 MB 1,024 KB or 1,0242 bytes

1 GB 1,024 MB or 1,0243 bytes

1 TB 1,024 GB or 1,0244 bytes

1 PB 1,024 TB or 1,0245 bytes

Value

Preface 13

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Logical capacity unit Value

1 EB 1,024 PB or 1,0246 bytes

Accessing product documentation

Product user documentation is available on Hitachi Data Systems Support
Connect:
most current documentation, including important updates that may have
been made after the release of the product.

https://knowledge.hds.com/Documents. Check this site for the

Getting help

Hitachi Data Systems Support Connect is the destination for technical support

of products and solutions sold by Hitachi Data Systems. To contact technical
support, log on to Hitachi Data Systems Support Connect for contact
information:

Hitachi Data Systems Community is a global online community for HDS

customers, partners, independent software vendors, employees, and
prospects. It is the destination to get answers, discover insights, and make
connections. Join the conversation today! Go to
register, and complete your profile.

https://support.hds.com/en_us/contact-us.html.

community.hds.com,

Comments

Please send us your comments on this document to [e-mail].
Include the document title and number, including the revision level (for
example, -07), and refer to specific sections and paragraphs whenever
possible. All comments become the property of Hitachi Data Systems
Corporation.

Thank you!

14 Preface

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

1

Overview of Thin Image

With Hitachi Thin Image (HTI), you can perform cost-effective replication by
storing the differential data between primary volumes (P-VOLs) and
secondary volumes (S-VOLs) of virtual volumes (V-VOLs). You can also copy
data of an entire volume, instead of copying just the differential data, to a
volume. By copying the entire volume, you can expect a higher performance
than by just storing the differential data.

About Thin Image

□

Components of Thin Image

□

How Thin Image works

□

How Thin Image pair status changes

□

Copy threshold option and host server I/O performance for Thin Image

□

Sharing Thin Image volumes with other software applications

□

System option modes for Thin Image

□

Acronyms and abbreviations for VSP family storage system software

□

applications used in this guide

Overview of Thin Image 15

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

About Thin Image

Hitachi Thin Image stores snapshots in a Hitachi Virtual Storage Platform
family (VSP family) storage system. If the data of the storage system fails,
you can restore it using the stored snapshot of the data. Pairs created by
using Thin Image are called Thin Image pairs in this document.

To store snapshot data, you create a pair with a logical volume functioning as
the P-VOL, and a virtual volume as the S-VOL. A pair created to store
snapshot data is referred to as a snapshot pair. A snapshot pair displays
showing the snapshot attribute.

When you create a Thin Image pair, the status changes to "PAIR" and
snapshot data is stored. You can use Thin Image to store a maximum of
1,024 snapshots of data (including the number of clones when you clone a
volume).

Updating the P-VOL first copies the differential data as snapshot data in pool
volumes (pool-VOL), and then updates the data. Snapshot data is a copy of
differential data in Thin Image P-VOLs. If your storage system experiences a
data storage failure, you can restore the data using the snapshot data in the
pool.

Splitting a Thin Image pair saves a snapshot and stops the copying of
replaced data in the pool.

The following figure provides a basic illustration of storing snapshot data.

16 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

You can use snapshot data in open-system volumes.

Related concepts

• How Thin Image uses V-VOLs on page 28

Related tasks

•

Splitting Thin Image pairs to store snapshot data on page 136

Workflow for storing Thin Image snapshot data

Snapshot data is data in the pool, which is replaced data. Use this workflow
to store snapshot data in the pool.

1. Create a Thin Image pair. You can create a pair with the snapshot
attribute (snapshot pairs). The pair is in "PAIR" status.

2. The host updates the primary volume.

3. Split the snapshot pairs. The snapshot data of the primary volume is

stored (Snapshot data A in the figure below).

4. The host updates the primary volume again.

5. Split the snapshot pairs. The updated data in the primary volume is

stored as snapshot data (Snapshot data B in the following figure). In the
event of data corruption, you can recover using this snapshot data.

The following figure illustrates how data in the pool is replaced.

Overview of Thin Image 17

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Note: Because Snapshot data A and Snapshot data B are handled as a Thin
Image S-VOL of a snapshot pair, the host can reference the P-VOL, Snapshot
data A, and Snapshot data B.

Components of Thin Image

Hitachi Thin Image typically consists of several components, including pairs,
groups, and software applications. Thin Image requires Dynamic Provisioning,
which is used to access data for open-system servers such as UNIX and PC
servers in a pool volume through a virtual volume.

Thin Image components:

• Hitachi Thin Image pairs (clone and snapshot pairs).

• Volume related components (P-VOL, S-VOL, and pools)

• Snapshot tree related components (root volume, node volumes, and leaf

volumes)

Groups:

• Consistency groups

• Snapshot groups

Software applications for VSP family storage systems:

• Hitachi Thin Image

• Dynamic Provisioning (HDP)

• Command Control Interface (CCI)

You can run CCI commands to perform Thin Image tasks (see Pair tasks

using CCI or Device Manager - Storage Navigator on page 212).

Thin Image pairs

This table describes Thin Image pairs.

Type

Pairs with the
snapshot attribute

Volume that can
be used as P-VOL

Logical volume
(LDEV)

Volume that can
be used as S-VOL

Thin Image V-VOL
(V-VOL of which
provisioning type
is Snapshot)

DP-VOL Yes

Cascade
capability

No

Description

Pairs used to
store snapshot
data.

The logical
volume of the P­VOL contains DP­VOLs (V-VOL of
which provisioning
type is Dynamic
Provisioning).

Pairs used to
store snapshot
data. To create a
cascaded pair with

18 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Type

Pairs with the
clone attribute

Volume components

To create Thin Image pairs, the following volumes are required.

Volume that can
be used as P-VOL

Logical volume
(LDEV)

Volume that can
be used as S-VOL

DP-VOL Yes

Cascade
capability

Description

the snapshot
attribute, use a
DP-VOL as the S­VOL.

The logical
volume of the P­VOL contains DP­VOLs (V-VOL of
which provisioning
type is Dynamic
Provisioning).

Pairs to be cloned.

The logical
volume of the P­VOL contains DP­VOLs (V-VOL of
which provisioning
type is Dynamic
Provisioning).

Volume type Volumes that can be used Description

Primary Logical volume (LDEV) Logical volume of a P-VOL

contains DP-VOLs (V-VOLs of
which provisioning type is
Dynamic Provisioning).

Secondary Thin Image V-VOL (V-VOL of

which provisioning type is
Snapshot)

DP-VOL

Pool Logical volume (LDEV) Volumes that configure a pool

Use this volume to create
snapshot pairs. Cannot be used
for cascaded or cloned pairs.

This volume is required to
create a pair with the S-VOL
specified.

Use this volume to create
cascaded or cloned pairs.

This volume is required to
create a pair with the S-VOL
specified. Cloned pairs must be
created with the S-VOL
specified.

which stores snapshot data.
Differential data of a P-VOL is
stored in a pool volume as
snapshot data.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Snapshot tree components

A snapshot tree contains the following volumes.

Volume type Volumes that can be used Description

Root Logical volume (LDEV)

Node DP-VOL

Leaf DP-VOL

Consistency and snapshot groups

Consistency groups and snapshot groups are groups of pairs for which you
can simultaneously perform pair tasks on all pairs within the group.

Volume (L1 pair of the P-VOL)
in the top layer of a snapshot
tree.

The logical volume of the P-VOL
contains DP-VOLs (V-VOL of
which provisioning type is
Dynamic Provisioning).

Volumes located between the
root volume and leaf volumes.

S-VOL of the root volume (or
another node volume), and the
P-VOL of a leaf volume (or
another node volume).

Volumes in the bottom layer of
a snapshot tree.

S-VOL of the root volume or a
node volume, which is not a P­VOL of any pair.

A consistency group can include Thin Image (HTI), ShadowImage (SI), and
ShadowImage for Mainframe (SIz) pairs. Use consistency groups to split the
Thin Image pairs that are defined in the group. Splitting the pairs using the
group assures data consistency at the time the VSP family storage system
receives the request.

A snapshot group is a group of only Thin Image pairs. Use consistency or
snapshot groups to perform Thin Image tasks on all of the pairs within the
group. You define Thin Image pairs to a snapshot group when you create the
pairs.

The following table shows the differences between consistency groups and
snapshot groups.

Item

Pair limit per group 8,192 8,192

Limit 2,048 2,048

Data consistency Guaranteed Not guaranteed

Software application from which you can define pairs HTI, SI, and SIz HTI

Consistency group Snapshot group

20 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

For more information about defining TC pairs in consistency groups, see the
Hitachi TrueCopy® User Guide.

For more information about defining UR pairs in consistency groups, see the
Hitachi Universal Replicator User Guide.

For more information about defining SI pairs in consistency groups, see the
Hitachi ShadowImage® User Guide.

Related concepts

•

Workflow for creating groups and storing snapshot data using CCI on

page 33

Related tasks

• Creating Thin Image pairs and defining them in snapshot or consistency

groups using CCI on page 134

• Removing Thin Image snapshot groups on page 148

Related references

• Pair tasks using CCI or Device Manager - Storage Navigator on page 212

Snapshot Clones

When distributing data in a storage system, you can use clones to improve
efficiency.

The following figure illustrates cloning.

Overview of Thin Image 21

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

When cloning pairs, use a logical volume as the P-VOL and a DP-VOL as the
S-VOL.

If you split pairs that have the clone attribute, the data of the entire P-VOL is
copied to the S-VOL asynchronously to create a clone of the primary volume.
When the copy completes, pairs are deleted and the S-VOL is unpaired
(becomes a DP-VOL). This volume can be used as a volume in the same
status as the P-VOL. This operation is referred to as cloning pairs.

A maximum of 1,024 clones (including the number of snapshots if you store
them) can be created by using Thin Image.

Cloning pairs includes operations after the P-VOL is copied to the S-VOL, until
volumes are unpaired. Volumes created by cloning are not included.

Snapshot trees and cascaded pairs

Snapshot trees are Thin Image pair configurations where snapshot data is
stored.

The volume in the top layer of the snapshot tree is the root volume. Volumes
in the bottom layer are leaf volumes.

Creating cascaded pairs

Thin Image S-VOLs can be paired with secondary layer S-VOLs. First layer
(L1) S-VOLs can also be paired with secondary layer (L2) S-VOLs. A

22 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

maximum of 64 layers can be created, and a maximum of 1,024 S-VOLs can
be used for a P-VOL. In this case, the snapshot tree is cascaded.

L2 to L64 pairs are called cascaded pairs. The following figure illustrates the
configuration of cascaded snapshot trees.

• The volume in the top layer of the snapshot tree (P-VOL of the L1 pair) is

the root volume.

• Volumes between the root and leaf volumes are node volumes.

• Volumes in the bottom layer of the snapshot tree are leaf volumes.

To create a Thin Image pair that can be used in a cascaded snapshot tree,
open the Create TI Pairs window and select Enable for Cascade. For details,

Overview of Thin Image 23

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

see Creating Thin Image pairs using Device Manager - Storage Navigator on

page 130.

When the S-VOL of a Thin Image pair you created for a P-VOL for the first
time is a DP-VOL, you can create cascaded pairs. If a Thin Image pair whose
secondary volume is a Thin Image V-VOL (which has the Snapshot
provisioning type) is created, remove the pair first, and then create another
Thin Image pair whose secondary volume is a DP-VOL.

A snapshot tree can be configured by combining snapshot and cloned pairs.
As shown in the following figure, you can also cascade pairs that are being
cloned, but you can only clone up to three pairs concurrently. The following
figure shows an example of when pairs that are being cloned are also
cascaded.

24 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

You can use the S-VOL of a cascaded and cloned pair as a new L1 pair of the
P-VOL. In this case, the volume is the root volume, and a node or leaf
volume.

VSP family software applications for Thin Image

A Thin Image installation typically includes the Thin Image software, Dynamic
Provisioning software, and CCI.

Overview of Thin Image 25

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Thin Image

Use the Thin Image software on the Device Manager - Storage Navigator
(HDvM - SN) computer that is connected to the service processor (SVP) by
means of the TCP/IP local area network (LAN).

Dynamic Provisioning

Use the HDP software on the HDvM - SN computer. A user license is required
to use HDP.

Since Thin Image uses a portion of the HDP licensed capacity for its pool
capacity, reserve enough HDP licensed capacity to run both HDP and Thin
Image and to accommodate the Thin Image pairs or pools that you will
create.

Thin Image and HDP pool-VOLs are also referred to as used volumes. The
licensed capacity must exceed the total capacity of used volumes.

CCI

When you use CCI to define multiple Thin Image pairs in a consistency group,
you can only specify one consistency group for a group defined by the
configuration definition file for CCI.

Note: The configuration definition file for CCI is a group that is not a
consistency group.

If you create a new pair and define the pairs in a consistency group for a
group you defined using the configuration definition file for CCI, and the pair
is already defined in a consistency group, the pair is defined in the same
consistency group even if you try to create a new pair and assign it to a
different consistency group.

Related tasks

•

Splitting Thin Image pairs to store snapshot data using CCI on page 137

How Thin Image works

This topic explains how Thin Image works.

How Thin Image uses pools and pool volumes

Thin Image stores snapshot data in DP pools (Pool Type: Dynamic
Provisioning) or Thin Image pools (Pool Type: Thin Image). Unless they are
defined otherwise, both DP pools and Thin Image pools are referred to as
"pools". A pool consists of multiple pool volumes (pool-VOLs) which are, as a
group, the container for the snapshot data.

26 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

You must create pools to use Thin Image. You can create pools and add and
delete pool-VOLs from them using Thin Image.

The following figure illustrates the relationship between a Thin Image pair
and a pool.

Caution: When creating pools, calculate the pool capacity and reserve a
sufficient amount of pool capacity. When you write data to Thin Image pair
volumes and the amount of pool usage exceeds the pool capacity, the Thin
Image pair is suspended (“PSUE” status), snapshot data is not stored, and
you cannot create additional Thin Image pairs.

Related tasks

• Creating Thin Image data pools on page 101

• Increasing pool capacity on page 173

• Decreasing pool capacity on page 177

• Deleting pools on page 187

•

Restoring suspended Thin Image pairs on page 143

Usage level rebalancing among parity groups

If multiple parity groups that contain LDEVs used as pool-VOLs exist,
rebalancing can improve biased usage rates in parity groups.

Overview of Thin Image 27

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Rebalancing is performed as if each parity group were a single pool-VOL.
After rebalancing, the usage rates of LDEVs in a parity group may not be
balanced, but the usage rate in the entire pool is balanced.

The usage level among parity groups is automatically rebalanced when
expanding or shrinking pool capacity operations are in progress.

If you expand the pool capacity, Dynamic Provisioning moves data to the
added space on a per-page basis. When the data is moved, the usage rate
among parity groups of the pool-VOLs is rebalanced.

Host I/O performance may decrease when data is moved. If you do not want
to have the usage level of parity groups automatically balanced, call
customer support.

You can see the rebalancing progress of the usage level among parity groups
in the View Pool Management Status window. Dynamic Provisioning
automatically stops balancing the usage levels among parity groups if the
cache memory is not redundant or the pool usage rate reaches up to the
threshold.

Related tasks

•

Viewing formatted pool capacity and pool usage rates on page 173

How Thin Image uses V-VOLs

V-VOLs are virtual volumes that do not have any physical storage space.

Thin Image uses V-VOLs (V-VOLs of provisioning type Snapshot) or DP-VOL
as V-VOLs. Thin Image V-VOLs and DP-VOLs are referred to as virtual
volumes (V-VOLs) in this document. Use DP-VOLs to create cascaded or
cloned pairs. Use Thin Image V-VOLs to create snapshot pairs. Note that you
can use DP-VOLs to cascade snapshot pairs.

Thin Image uses V-VOLs to access snapshot data from hosts or clone pairs,
so if you create clone pairs or use snapshot pairs (a pair with the snapshot
attribute) to access snapshot data from hosts, then V-VOLs are required to
create Thin Image pairs or assign an S-VOL to snapshot data. If the storage
system or snapshot pair does not need to access snapshot data from hosts,
V-VOLs are not necessary.

You can release the V-VOLs that are being used as Thin Image S-VOLs from
assignment of snapshot data. Released V-VOLs can be assigned to other
snapshot data. However, you cannot release allocation of V-VOLs used as
node volumes to snapshot data or allocate the V-VOL to different snapshot
data. Also, you cannot release allocation of V-VOLs which are being used for
the S-VOL of a clone pair to snapshot data, or allocate it to different snapshot
data.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

You cannot release definitions of V-VOLs if the V-VOLs are being used as Thin
Image secondary volumes; you must first release the Thin Image pairs that
are using the V-VOLs.

How Thin Image pairs are created

When creating a Thin Image pair, you need to specify the pool to be used for
the pair. If multiple Thin Image pairs share the same primary volume, the
pairs must also share the same pool. For example, if you specify three
secondary volumes for one primary volume, you must specify the same pool
for the three Thin Image pairs.

If you release a Thin Image pair, the volume status becomes SMPL.
Immediately after a volume becomes SMPL, you cannot use the volume to
create a Thin Image pair. If you want to create Thin Image pairs using SMPL
volumes, you should wait for a while before creating the pairs. The wait time
required depends on your system environment.

Related tasks

•

Creating Thin Image pairs using Device Manager - Storage Navigator on

page 130

• Viewing pair properties on page 160

Using snapshot pairs (not cascaded)

The following figure shows how snapshot pairs are used when they are not
cascaded.

Data in the P-VOL is backed up one time every day. The P-VOL can be
restored using the S-VOL if a logical failure occurs during data update or if
there is a virus in the P-VOL.

Overview of Thin Image 29

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Using cascaded pairs

Distributing data in the P-VOL to multiple users

Create the same number of leaf volumes as the number of users to whom
you want to distribute data. This allows you to distribute data in the P-VOL
without increasing loads to the P-VOL.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Distributing updated data in the P-VOL to specified users

Overview of Thin Image 31

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

When you update the P-VOL and want to give it only to the specified users
(S-VOLs 5 and 6 in the figure), do the following:

1. Create cascaded pairs, and distribute data in the P-VOL. Assign users to
whom you want to distribute the updated data, and users to whom you
do not want to distribute the updated data to separate node volumes.

2. Delete the pairs in the node volume where you assigned users you do not
want to distribute the updated data to (S-VOL 1 in the figure).

3. Update the P-VOL.

Creating a new distributor with cloned pairs

32 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

1. Create cascaded pairs and distribute data in the P-VOL. Assign the clone
attribute to the volume to be a new distributor (S-VOL 3 in the figure).

2. Clone pairs.

By cloning pairs, S-VOL 3 and S-VOL 1 become unpaired volumes (DP-VOLs)
in the same status, and S-VOL 3 can be a new distributor. As a result, the
overhead of the Thin Image pairs can be reduced.

Workflow for creating groups and storing snapshot data using CCI

You can use CCI raidcom commands to create a consistency or snapshot
group and to split pairs to store the snapshot data for the group.

With Thin Image, ShadowImage, and ShadowImage for Mainframe, you can
create up to 2,048 consistency groups in a VSP family storage system.

The following figure illustrates how snapshot data is stored for a consistency
or snapshot group using CCI raidcom commands.

Overview of Thin Image 33

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Use the following workflow to create a snapshot group and store volume
snapshot data in the group:

1. Split the pair and store snapshot data for a group. To do this using CCI,
run the following raidcom command:

raidcom modify snapshot -snapshot_data create

2. The host issues a write request to each P-VOL in the group.
Snapshot data for the volumes are stored.

34 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

A CCI command is used to store snapshot data for a consistency group or a
snapshot group. Device Manager - Storage Navigator can only be used to
reference consistency groups and snapshot groups.

Related concepts

• Consistency and snapshot groups on page 20

Related tasks

• Creating Thin Image pairs using Device Manager - Storage Navigator on

page 130

• Removing Thin Image snapshot groups on page 148

Related references

• Pair tasks using CCI or Device Manager - Storage Navigator on page 212

Methods of storing snapshot data

The Copy-After-Write (CAW) method is the default method of storing
snapshot data. However, if the write pending rate (percentage of data waiting
to be written in cache memory) is 60% or higher when writing in cascaded
pairs random access mode, or 30% or higher when writing in sequential
access mode, the Copy-On-Write (COW) method is used.

In the CAW method, writing the P-VOL snapshot data changes the status to
“write completion”. In the COW method, storing the P-VOL snapshot data
changes the status to "write completion". The CAW method wait time is
shorter than that of the COW method.

Workflow for the CAW method

The following workflow describes the CAW method and how a VSP G series or
VSP F series storage system stores snapshot data:

1. The host writes data to a P-VOL.

2. The storage system returns the write completion status to the host.

3. The storage system stores snapshot data for the P-VOL in the

background.

The following figure illustrates the CAW method.

Overview of Thin Image 35

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Workflow for the COW method

The following workflow describes the COW method and how a VSP G series or
VSP F series storage system stores snapshot data:

1. The host writes data to a P-VOL.

2. The storage system stores snapshot data for the P-VOL.

3. The storage system returns the write completion status to the host.

The following figure illustrates the COW method.

36 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Thin Image pair restoration

You can use Thin Image to overwrite snapshot data in pools to P-VOLs so that
the P-VOL content is returned to the condition it was when you stored
snapshot data.

Overwriting snapshot data to P-VOLs is also referred to as restoring Thin
Image pairs.

If data is written to a secondary volume, this particular data (not snapshot
data) is overwritten to the primary volume when the Thin Image pair is
restored.

If a problem occurs in P-VOL data due to a failure, restoring the pair restores
the P-VOL data saved when the snapshot data was stored.

The time for restoring a Thin Image pair depends on the following, even if the
pair synchronization rate is 100%:

• The amount of pool capacity a pair is using.

• The number of pairs being operated concurrently.

The pair synchronization rate shows the rate that S-VOL data matches that of
the next generation of the S-VOL. If the S-VOL is the latest one, the
synchronization rate is computed by comparing the S-VOL with the P-VOL.

For the Thin Image pair where the cascade attribute is enabled, the
information displayed in Synchronization Rate (%) of the View Pair
Synchronization Rate window varies depending on the pair status.

Related tasks

•

Restoring Thin Image pairs on page 141

How Thin Image pair status changes

The Thin Image pair status changes as you create, split, or perform other
pair tasks.

The following figure illustrates status changes to Thin Image and snapshot
pairs.

Overview of Thin Image 37

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

The following workflow describes the Thin Image pair status changes:

1. You choose two volumes that are in SMPL status and are not in use as a
Thin Image pair.

2. You create a pair. If the primary volume has not previously been paired
with any secondary volume, the pair status changes to "COPY" at first,
and then to "PAIR" after the pair creation finishes.

• Creation of a Thin Image pair may be time consuming if you create a

pair immediately after deleting the last snapshot data for the primary
volume.

• If the pool threshold is exceeded when the Thin Image pair is in

"PAIR" status, the pair status changes to "PFUL."

• Thin Image pairs cannot be created when the pool threshold (warning

threshold when snapshot data is stored in a DP pool) is exceeded.

3. Snapshot data is stored when you split a pair in "PAIR" status. After
snapshot data is stored, the pair status is "PSUS." If the pool threshold is

38 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

exceeded when the Thin Image pair is in "PSUS" status, the pair status
changes to "PFUS."

4. If you only want to delete snapshot data but do not want to release the
Thin Image pair, you delete the snapshot data for the pair in "PSUS" or
"PFUS" status.

5. If you restore a Thin Image pair in "PSUS" status, snapshot data is
overwritten to the primary volume. The pair status is "COPY(RS-R) or
RCPY" when the restore process is in progress. The pair status is "PAIR"
after the restore process finishes.

6. The pool can only contain data of predetermined capacity. If the total
capacity of snapshot data in the pool exceeds the pool capacity, the
status of the Thin Image pair becomes "PSUE." In addition, the pair
status changes to "PSUE" if a failure occurs during the restore process or
if the pool usage rate reaches 100 percent. Even if the restore process is
not in progress, the pair status may change to "PSUE" when a failure
occurs. When snapshot data is stored in the DP pool, the timing of
changing to PSUE is determined by the setting in "Suspend TI pairs when
the deletion threshold is exceeded". For details, see the Provisioning
Guide for your storage system.

Thin Image host access and pair status

The status of Thin Image (HTI) pairs depends on whether the hosts can read
from or write to the Thin Image pair P-VOL or S-VOLs.

The following table explains the host access and pair status for snapshot
pairs.

P-VOL S-VOL

HTI pair status

Read Write Read Write

SMPL Yes Yes No No

SMPL(PD) or SMPP Yes Yes No No

COPY Yes Yes No No

PAIR/PFUL Yes Yes No No

PSUS/PFUS Yes Yes Yes Yes

COPY(RS-R) or RCPY Yes Yes No No

PSUE Yes Yes No No

Legend

Yes: Hosts can access the volume

No: Hosts cannot access the volume

Caution: If a host uses a software application to monitor Thin Image pair
volumes other than Thin Image, the S-VOL status determines if the software
application ends abnormally. For example, if the S-VOLs are in a status other
than "PSUS" and "PFUS," the host can reject access.

Overview of Thin Image 39

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

If a host connects to at least two ports, an abnormality can occur with ports
that are not connected to S-VOLs rejecting access from hosts. To resolve
these issues, close the software application that monitors volumes.

Workflow for Thin Image pair status changes

The following figure illustrates status changes to Thin Image cloned pairs.

The following workflow describes Thin Image pair status changes:

1. You choose two volumes that are in the SMPL status and are not in use
as a Thin Image pair.

2. You create a pair. If the P-VOL has not previously been paired with any
S-VOL, the pair status changes to COPY at first, and then to PAIR after
the pair creation finishes.

3. You split a pair. When you split a pair in the PAIR status, the pair status
changes to PSUS(SP) or PSUP, and copying data is started
asynchronously. When the copy operation completes, the pair status
changes to SMPL(PD) or SMPP. When the pair deletion completes, the
pair status changes to SMPL. The S-VOL becomes unpaired (a DP-VOL)
and can be used as a volume in the same status as the P-VOL.

Note: If you delete a pair when the pair status is PSUS(SP) or
PSUP, copying data stops at the time when the pair deletion is
accepted, and the status changes to SMPL. If this happens, data in
the S-VOL is not guaranteed.

40 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

4. The DP pool can only contain data of predetermined capacity. If the total
capacity of data in the pool exceeds the pool capacity, the status of the
Thin Image pair changes to PSUE. In addition, the pair status also
changes to PSUE if a failure occurs during the process or if the pool
usage rate reaches 100 percent. When snapshot data is stored in the DP
pool, the timing of changing to PSUE is determined by the setting in
"Suspend TI pairs when the deletion threshold is exceeded". For details,
see the Provisioning Guide for your storage system.

5. You delete a pair. When a pair is deleted, the pair status changes to
SMPL(PD) or SMPP. After that, it changes to SMPL when pair deletion
completes.

Whether the host can read or write data from and to a Thin Image pair P-VOL
or S-VOL is determined by the pair status. The following table describes
whether the host can access volumes, and their cloned pair status.

Primary volume Secondary volume

Pair status

Read Write Read Write

SMPL Y Y Y Y

COPY Y Y N N

PAIR Y Y N N

PSUS(SP) or PSUP Y Y Y Y

SMPL(PD) or

SMPP

PSUE Y Y N N

Y Y Y Y

Copy threshold option and host server I/O performance for Thin Image

You can enable the copy threshold option to help minimize the decline of host
server I/O performance by lowering the workload on the storage system.

I/O performance of the host server might be lowered as the workload on the
storage system increases. If you perform Thin Image restore operations
when the workload on the storage system is high, I/O performance of the
host server is more likely to be lowered because replication processes for the
primary volumes are triggered. The copy threshold option can be used to
temporarily stop the replication processes triggered by the restore operations
when the workload on the storage system is high. The copy threshold option
can contribute to minimizing the decline in I/O performance of the host
server.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

The copy threshold option is applicable only when the workload on the
storage system is excessively heavy. If the copy threshold option is applied,
all the replication processes triggered by restore operations are stopped.

Replication processes stopped by the copy threshold option will be restarted
as the workload on the storage system is lowered. Enabling the copy
threshold option stops replication processes for Thin Image and the following
products when the storage system is overloaded.

• ShadowImage

• ShadowImage for Mainframe

• Compatible FlashCopy® V2

• Volume Migration V2

For more information about enabling the copy threshold option, call customer
support.

For more information about Compatible FlashCopy® V2, see the Hitachi
Compatible FlashCopy/FlashCopy SE User Guide.

Related concepts

•

Thin Image pair restoration on page 37

Sharing Thin Image volumes with other software applications

You can create Thin Image (HTI) pairs using pair volumes for other
replication software applications, such as ShadowImage and TrueCopy. You
can also create Thin Image pairs using volumes to which you define
attributes using Data Retention Utility or CCI.

You can share Thin Image volumes with the following software application
volumes:

• Data Retention Utility (VSP G1000, G1500, and VSP F1500)

• Volume Migration V2

• ShadowImage (SI)

• TrueCopy (TC)

• Universal Replicator (UR)

• Global-active device (GAD)

The following table shows when you can share Thin Image pair volumes with
other software application volumes. If a volume that you share with a Thin
Image volume is shown in the table, the pair status determines whether you
can perform tasks. If the S-VOL is not assigned to snapshot data, you cannot
share Thin Image volumes with other software applications, because the S­VOL does not exist.

42 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Note: For node or leaf volumes, see the Used as an HTI S-VOL column
instead of the Used as an HTI P-VOL column.

Software application volume type Used as an HTI P-VOL Used as an HTI S-VOL

SI P-VOL Yes

3

No

SI S-VOL Yes No

TC P-VOL Yes No

TC S-VOL Yes No

UR P-VOL Yes No

UR S-VOL Yes No

UR journal volume No No

GAD P-VOL Yes No

GAD S-VOL Yes No

GAD volume with reservation attribute No No

GAD volume for quorum disk No No

Volume Migration source volume No No

Volume Migration target volume No No

1, 4, 6

2, 5, 6

1, 4, 6

4, 6

2, 5, 6

Yes Yes

Yes Yes

Yes No

Yes Yes

Yes Yes

Yes

Yes

No No

7

8

Read Only volume

Protect volume

S-VOL Disable volume

Zero Read Capacity volume

Invisible volume

DP-VOL Yes Yes

V-VOL with capacity saving enabled

Deduplication system data volume

1. If you use HDvM - SN to share the volume with other software applications, the pair status
determines whether you can share the volume.

2. To share the volume with other software applications, you must use CCI.

3. You cannot Quick Restore.

4. Use the Data Retention Utility (VSP G1000, G1500, and VSP F1500) to set this attribute.

5. Use CCI to set this attribute.

6. Use the Data Retention Utility (VSP G1000, G1500, and VSP F1500) to confirm whether this

attribute is set to volume.

7. Can be shared if the pair is cascaded or has the clone attribute.

8. Can be set on an S-VOL of a cascaded pair or a clone attribute pair. Note that only the clone

attribute enables capacity saving.

Legend:

Yes: You can share the volume.
No: You cannot share the volume.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Sharing Thin Image volumes that have Data Retention Utility access attributes

You can create Thin Image (HTI) pairs using volumes on which you set Data
Retention Utility access attributes. In addition, you can set any access
attribute for virtual volumes of HTI.

Depending on access attributes of the P-VOL, S-VOL, or pool volume, you
cannot perform some pair tasks and pool tasks with Thin Image. The Thin
Image pair tasks you can perform are different depending on whether you
assign Data Retention Utility access attributes using CCI or HDvM - SN. The
tables below explain whether you can perform Thin Image pair tasks and pool
tasks on volumes that have access attributes assigned by Data Retention
Utility. If you release assignment of snapshot data after assigning access
attributes to a Thin Image S-VOL, the Thin Image tasks you can perform are
the same as those that can be performed when the Read/Write attribute is
assigned to the S-VOL.

Also, you can assign access attributes to Thin Image P-VOL and S-VOLs. The
tables below also explain Thin Image pair tasks and pool tasks after access
attributes are assigned.

Access attributes and supported Thin Image pair tasks

The following table lists the relationship between P-VOL and S-VOL access
attributes and Thin Image pair tasks when using HDvM - SN to assign Data
Retention Utility access attributes.

Volume access attributes specified for the HTI pair

Create, split,

P-VOL S-VOL

Read/Write Read/Write Yes

Read Only, Protect, S-VOL
Disable

Read Only, Protect, S­VOL Disable

1. Reverse Copy does not copy S-VOL access attributes to P-VOLs (see Pair resynchronization

methods on page 143).

Read/Write Yes No Yes

Read Only, Protect, S-VOL
Disable

suspend,

Resync pair

(Normal Copy)

No

No

HTI pair task

Resync

(Reverse

Copy)

1

Delete

The following table lists the relationship between P-VOL and S-VOL access
attributes and Thin Image pair tasks when using CCI to assign Data
Retention Utility access attributes.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Volume access attributes specified for the HTI pair HTI pair task

Create, split,

P-VOL S-VOL

Read/Write, Read Only,
Protect

S-VOL Disable Read/Write, Read Only,

1. Reverse Copy does not copy S-VOL access attributes to P-VOLs (see Pair resynchronization

methods on page 143).

Read/Write, Read Only,
Protect

S-VOL Disable No

Protect

S-VOL Disable No

suspend,

Resync pair

(Normal Copy)

Yes

Yes No Yes

Resync

(Reverse

1

Copy)

Delete

Access attributes and supported Thin Image pool tasks

The following table lists the relationship between P-VOL and S-VOL access
attributes specified by Thin Image and Thin Image pool tasks when using CCI
or HDvM - SN to assign Data Retention Utility access attributes.

Volume access attributes specified by HTI Pool-VOL setting

Read/Write Yes

Read Only No

Protect No

S-VOL Disable No

Legend:

Yes: You can perform the task.
No: You cannot perform the task.

Note: Performing a Thin Image task does not change the volume access
attributes.

Required Thin Image pair status when using Data Retention Utility to assign
access attributes to some volumes

The following table shows the Thin Image pair status that is required to use
Data Retention Utility to assign access attributes to some Thin Image P-VOLs
and S-VOLs when also using HDvM - SN to assign Data Retention Utility
access attributes.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

HTI volume Access attribute to be assigned

Read Only

Pair status Volume Read/Write

COPY P-VOL Yes Yes

S-VOL Yes No

PAIR, PFUL P-VOL Yes Yes

S-VOL Yes Yes

PSUS, PFUS P-VOL Yes Yes

S-VOL Yes Yes

SMPL(PD) P-VOL Yes Yes

S-VOL Yes No

RCPY P-VOL Yes No

S-VOL Yes No

PSUE P-VOL Yes Yes

S-VOL Yes No

Legend:

Yes: You can perform the setting
No: You cannot perform the setting.

Protect

S-VOL Disable

The following table shows the Thin Image pair status that is required to use
Data Retention Utility to assign access attributes to some Thin Image P-VOLs
and S-VOLs when also using CCI to assign Data Retention Utility access
attributes.

HTI volume

Pair status Volume

COPY P-VOL Yes Yes

S-VOL Yes No

PAIR, PFUL P-VOL Yes Yes

S-VOL Yes Yes

PSUS, PFUS P-VOL Yes Yes

S-VOL Yes Yes

SMPL(PD) P-VOL Yes Yes

S-VOL Yes No

RCPY P-VOL Yes No

S-VOL Yes No

Access attribute to be assigned

Read/Write

Read Only

Protect

S-VOL Disable

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

HTI volume Access attribute to be assigned

Read/Write

Pair status Volume

PSUE P-VOL Yes Yes

S-VOL Yes No

Legend:

Yes: You can perform the setting
No: You cannot perform the setting.

Read Only

Protect

Sharing Thin Image volumes with Hitachi Volume Migration

You cannot do the following:

• Perform Thin Image tasks on volumes reserved for Volume Migration
without regard to the migration plan status.

• Use Thin Image pair volumes or pool-VOLs as volumes reserved for
Volume Migration V2.

For more information about the migration plan status and Volume Migration
tasks, see the Hitachi Volume Migration User Guide.

Sharing Thin Image volumes with ShadowImage

You can share Thin Image (HTI) P-VOLs with ShadowImage (SI) P-VOL and
S-VOLs.

S-VOL Disable

Available Thin Image tasks

The following table lists the Thin Image tasks you can perform when sharing
a Thin Image P-VOL with a ShadowImage P-VOL.

SI pair status

HTI task

Create pair Yes Yes Yes Yes Yes Yes No Yes

Store snapshot data Yes Yes Yes Yes Yes Yes No Yes

Restore pair No No No No Yes No No Yes

Delete snapshot
data

Release pair Yes Yes Yes Yes Yes Yes Yes Yes

Legend:

Yes: You can perform the task.
No: You cannot perform the task (the command is rejected).

COPY(P

D)/

COPY

Yes Yes Yes Yes Yes Yes Yes Yes

PAI

R

COPY(S

P)/

COPY

PSUS(S

P)/

PSUS

PSU

S

COPY(R

S)/

COPY

COPY(R

S-R)/
RCPY

PSU

E

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

The following table lists the Thin Image tasks you can perform when sharing
a Thin Image P-VOL with a ShadowImage S-VOL.

SI pair status

HTI task

Create pair No No No No Yes No No No

Store snapshot
data

Store snapshot
data for a
consistency group

Restore pair N/A No No No Yes No No No

Delete snapshot
data

Release pair N/A Yes Yes Yes Yes Yes Yes Yes

* The SI pair status must be "PSUS" during the period between when you create the HTI pair to
store snapshot data and when HTI starts to store snapshot data for a consistency group, and when
all of the pairs in the consistency group are split ("PSUS" status). If the SI pair status changes to a
status other than "PSUS" while HTI is storing snapshot data for the consistency group, the
snapshot data consistency cannot be guaranteed.

Legend:

Yes: You can perform the task.
No: You cannot perform the task (the command is rejected).
N/A: Not applicable.

COPY(P

D)/

COPY

N/A No No No Yes No No No

N/A No No No Yes*No No No

N/A Yes Yes Yes Yes Yes Yes Yes

PAIR

COPY(S

P)/

COPY

PSUS(S

P)/

PSUS

PSUS

COPY(R

S)/

COPY

COPY(R

S-R)/
RCPY

PSU

E

Available ShadowImage tasks

The following table lists the ShadowImage tasks you can perform when
sharing a Thin Image P-VOL with a ShadowImage P-VOL.

HTI pair status

SI task

COPY PAIR, PFUL

Create pair Yes Yes Yes Yes No Yes

Create and split pair Yes Yes Yes Yes No Yes

Split pair Yes Yes Yes Yes No Yes

Normal Copy Yes Yes Yes Yes No Yes

Reverse Copy Yes Yes Yes Yes No Yes

Quick Restore No No No No No No

Suspend replication Yes Yes Yes Yes Yes Yes

Delete pair Yes Yes Yes Yes Yes Yes

Legend:

Yes: You can perform the task.

PSUS,

PFUS

SMPL(PD) RCPY PSUE

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

HTI pair status

SI task

COPY PAIR, PFUL

No: You cannot perform the task (the command is rejected).

PSUS,

PFUS

SMPL(PD) RCPY PSUE

The following table lists the ShadowImage tasks you can perform when
sharing a Thin Image P-VOL with a ShadowImage S-VOL.

HTI pair status

SI task

COPY PAIR, PFUL

Create pair No No No No No No

Create and split pair No No No No No No

Split pair Yes Yes Yes Yes No Yes

Normal Copy Yes Yes Yes Yes No Yes

Reverse Copy Yes Yes Yes Yes No Yes

Quick Restore No No No No No No

Suspend replication Yes Yes Yes Yes No Yes

Delete pair Yes Yes Yes Yes Yes Yes

Legend:

PSUS,

PFUS

SMPL(PD)

RCP

Y

PSUE

Yes: You can perform the task.
No: You cannot perform the task (the command is rejected).

You can perform ShadowImage pair tasks after you store snapshot data, but
the consistency of the stored snapshot data is not guaranteed.

Thin Image S-VOLs use the data in the P-VOL. You cannot Quick Restore in
ShadowImage.

For more information about ShadowImage tasks and pair statuses, see the
Hitachi ShadowImage® User Guide.

Caution: Thin Image uses MU numbers 0 to 1,023, and they are assigned in
the order of 3 to 1,023, followed by 0 to 2. ShadowImage uses MU numbers
0 to 2. Thin Image cannot use the MU numbers 0 to 2 if you want to share
Thin Image volumes with ShadowImage.

To share Thin Image volumes with ShadowImage if Thin Image is using the
MU numbers 0 to 2:

1. Delete the Thin Image pair of the MU number 0 to 2.

2. Create the ShadowImage pairs and Thin Image pairs.

Sharing Thin Image volumes with TrueCopy and Universal Replicator

You can share Thin Image (HTI) P-VOLs with TrueCopy (TC) and Universal
Replicator (UR) pair volumes.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

The following tables list the relationship between pair tasks and status.

The following table lists the Thin Image tasks you can perform when the P­VOL is shared with a TrueCopy or Universal Replicator P-VOL.

TC/UR status

HTI task

COPY PAIR PSUS PSUE Suspending Deleting

Create pair Yes Yes Yes Yes Yes Yes

Store snapshot data Yes Yes Yes Yes Yes Yes

Restore pair No No Yes Yes No No

Delete snapshot data Yes Yes Yes Yes Yes Yes

Delete pair Yes Yes Yes Yes Yes Yes

Legend:

Yes: You can perform the task.
No: You cannot perform the task (the command is rejected).

The following table lists the Thin Image tasks you can perform when the P­VOL is shared with a TrueCopy or Universal Replicator S-VOL.

TC/UR status

HTI task

COPY PAIR PSUS PSUE SSWS Suspending Deleting

Create pair Yes Yes Yes Yes Yes Yes Yes

Store snapshot data No Yes Yes Yes Yes Yes Yes

Restore pair* No No No No No No No

Delete snapshot data Yes Yes Yes Yes Yes Yes Yes

Delete pair Yes Yes Yes Yes Yes Yes Yes

*When restoring an HTI pair and you are using the P-VOL as a TC or UR S-VOL, switch tasks to the
remote storage system using the horctakeover command.

Legend:

Yes: You can perform the task.
No: You cannot perform the task (the command is rejected).

The following table lists the TrueCopy/Universal Replicator tasks you can
perform when the Thin Image P-VOL is shared with a TrueCopy or Universal
Replicator P-VOL.

HTI status

TC/UR task

COPY PAIR, PFUL PSUS, PFUS RCPY PSUE

Create pair Yes Yes Yes No Yes

Split pair Yes Yes Yes N/A Yes

Resynchronize pair Yes Yes Yes No Yes

Delete pair Yes Yes Yes Yes Yes

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

HTI status

TC/UR task

COPY PAIR, PFUL PSUS, PFUS RCPY PSUE

Switch to remote storage Yes Yes Yes No Yes

Legend:

Yes: You can perform the task.
No: You cannot perform the task (the command is rejected).
N/A: Not applicable

The following table lists the TrueCopy/Universal Replicator tasks you can
perform when the Thin Image P-VOL is shared with a TrueCopy or Universal
Replicator S-VOL.

HTI status

TC/UR task

COPY PAIR, PFUL PSUS, PFUS RCPY PSUE

Create pair No No No No No

Split pair Yes Yes Yes N/A Yes

Resynchronize pair Yes Yes Yes N/A Yes

Delete pair Yes Yes Yes N/A Yes

Switch to remote storage Yes Yes Yes N/A Yes

*Use a TC/UR S-VOL as an HTI P-VOL.

Legend:

Yes: You can perform the task.
No: You cannot perform the task (the command is rejected).
N/A: Not applicable

Volume backup with Thin Image, TrueCopy, and Universal Replicator in a 3DC
multitarget configuration workflow

You can use Thin Image to back up TrueCopy and Universal Replicator
volumes on the remote sites in a 3DC multitarget configuration.

The following figure shows how to back up the volumes.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

• Pair 1 is a TrueCopy pair.

• Pair 2 is a Universal Replicator pair.

• Pair 3 is a Universal Replicator pair for delta resync.

• Pairs 4, 5, and 6 are Thin Image pairs.

You must create 3DC multitarget and delta resync pairs (pairs 1, 2, and 3)
before creating pairs 5 and 6, but pair 4 can be created at any time.

(VSP G200, G400, G600, G800 only) You cannot share 3DC volumes that use
two mirrors with Thin Image.

Volume backup with Thin Image and Universal Replicator in a 3DC multitarget
configuration workflow (VSP G1000, G1500, and VSP F1500)

You can use Thin Image to back up Universal Replicator volumes on the
remote sites in a 3DC multitarget configuration.

The following figure shows how to back up the volumes.

• Pairs 1 and 2 are Universal Replicator pairs.

• Pair 3 is a Universal Replicator pair for delta resync.

• Pairs 4, 5, and 6 are Thin Image pairs.

You must create pairs 1 and 2 before creating pairs 5 and 6, but pair 4 can
be created at any time.

Volume backup with Thin Image and Universal Replicator in a 3DC cascade
configuration workflow (VSP G1000, G1500, and VSP F1500)

You can use Thin Image to back up Universal Replicator volumes on the
remote sites in a 3DC cascade configuration.

The following figure shows how to back up the volumes.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

• Pairs 1 and 2 are Universal Replicator pairs.

• Pair 3 is a Universal Replicator pair for delta resync.

• Pairs 4, 5, and 6 are Thin Image pairs.

You must create pairs 1 and 2 before creating pairs 5 and 6, but pair 4 can
be created at any time.

Sharing Thin Image volumes with global-active device

You can use a Thin Image (HTI) P-VOL as a global-active device (GAD) P-VOL
or S-VOL.

The following tables list the relationship between Thin Image tasks and GAD
pair status.

Note: If you share GAD volumes with Thin Image volumes, stop I/O to a
volume before storing snapshot data. Snapshot consistency cannot be
guaranteed if you store snapshot data without stopping I/O to the volume.

For more information about GAD, see the Global-Active Device User Guide.

The following table lists the Thin Image tasks you can perform when the P­VOL is shared with a GAD P-VOL.

HTI task

GAD status

COPY Mirror

PAIR Mirror

PSUS Local Yes Yes Yes Yes Yes

PSUE Local Yes Yes Yes Yes Yes

I/O

mode

(RL)

(RL)

Block Yes Yes No Yes Yes

Create

pair

Yes Yes No Yes Yes

Yes Yes No Yes Yes

Store

snapshot

data

Restore

pair

Delete

snapshot

data

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Delete

pair

HTI task

GAD status

Legend:

Yes: You can perform the task.
No: You cannot perform the task (the command is rejected).

I/O

mode

Block Yes Yes No Yes Yes

Create

pair

Store

snapshot

data

Restore

pair

Delete

snapshot

data

Delete

pair

The following table lists the Thin Image tasks you can perform when the P­VOL is shared with a GAD S-VOL.

HTI task

GAD status

COPY Block No No No No Yes

PAIR Mirror

SSUS Block Yes Yes No Yes Yes

PSUE Block Yes Yes No Yes Yes

SSWS Local Yes Yes No Yes Yes

Legend:

I/O

mode

(RL)

Create

pair

Yes Yes No Yes Yes

Store

snapshot

data

Restore

pair

Delete

snapshot

data

Delete

pair

Yes: You can perform the task.
No: You cannot perform the task (the command is rejected).

Storage system configuration with Thin Image and GAD

Not all storage system configurations are supported when sharing a Thin
Image volume with a GAD volume.

When you create a Thin Image pair using a volume from a GAD pair, the
server recognizes the GAD P-VOL and S-VOL as a single volume. If you create
Thin Image pairs using both the P-VOL and S-VOL of a GAD pair, the server
recognizes the GAD P-VOL and S-VOL as a single volume being paired with
multiple volumes by Thin Image.

Supported configurations

The following figure shows a supported storage system configuration with a
Thin Image pair using a GAD P-VOL.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

The following figure shows a supported storage system configuration with a
Thin Image pair using a GAD S-VOL.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

The following figure shows a supported storage system configuration with
Thin Image pairs using a GAD P-VOL and S-VOL.

56 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Unsupported configuration

You cannot create a GAD pair using Thin Image volumes that are already
being used as a GAD P-VOL and S-VOL. The following figure shows this
unsupported storage system configuration.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Consistency group configuration with Thin Image and GAD

Not all consistency group configurations are supported when sharing a Thin
Image volume with a GAD volume.

Pairs in a Thin Image consistency group must be in the same storage system.
Therefore, if a GAD P-VOL and S-VOL are each used in Thin Image pairs, the
Thin Image pairs cannot be registered to the same consistency group.

Supported configuration

The following figure shows a supported consistency group configuration.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Unsupported configuration

The following figure shows an unsupported consistency group configuration.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Snapshot group configuration with Thin Image and GAD

Not all snapshot group configurations are supported when sharing a Thin
Image volume with a GAD volume.

Pairs in a Thin Image snapshot group must be in the same storage system.
Therefore, if a GAD P-VOL and S-VOL are each used in Thin Image pairs, the
Thin Image pairs cannot be registered to the same snapshot group.

Supported configuration

The following figure shows a supported snapshot group configuration.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Unsupported configuration

The following figure shows an unsupported snapshot group configuration.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Sharing Thin Image volumes with Dynamic Provisioning and Dynamic Provisioning for Mainframe in a single storage system

If you are using Thin Image, Dynamic Provisioning, and Dynamic Provisioning
for Mainframe in a single storage system, note the following when creating
Thin Image pairs:

• Data compressed or deduplicated by the capacity saving function is copied
to a volume. The capacity saving function is not performed immediately for
copied data. Before creating or resynchronizing a Thin Image pair, make

62 Overview of Thin Image

Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

sure that the available capacity in the copy destination volume is greater
than the used capacity in the copy origination volume. For details, see the
Provisioning Guide for Open Systems.

• If you create a Thin Image pair using a volume with the capacity saving
function enabled, the compressed or deduplicated data is copied. Because
of this, copy or I/O performance may be degraded.

• When the capacity saving function is used, management information is
stored in a pool. As a result, there may be difference between a P-VOL and
an S-VOL in the number of used pages or licensed capacity.

• The capacity saving function can be set on the P-VOL or S-VOL of a
cascaded or clone pair, but only works on the clone pair. The deduplication
system data volume cannot be used as a Thin Image P-VOL or S-VOL.

• You can create a Thin Image pair whose P-VOL or S-VOL is a Dynamic
Provisioning V-VOL only if you are not currently expanding the Dynamic
Provisioning V-VOL capacity.

• Performing a Thin Image paircreate operation while zero pages are being
reclaimed (including reclamation by Writesame, Unmap command, or
rebalancing) results in the zero-page operation being interrupted.

• Thin Image pair creation might be rejected if the Unmap command
operation is in progress with system option mode 905 ON. Wait a while
and then retry the operation. If the operation still fails, set system option
mode 905 to OFF and try again.

• You can use a maximum size Dynamic Provisioning volume as a Thin
Image P-VOL or S-VOL. For information about the maximum size for
Dynamic Provisioning volumes, see the Provisioning Guide for your storage
system.

Related tasks

•

Creating V-VOLs for Thin Image S-VOLs on page 113

• Creating Thin Image pairs using Device Manager - Storage Navigator on
page 130

Sharing Thin Image volumes with Resource Partition Manager

You can create a Thin Image pair without regards to the resource group
assignment of the P-VOL and S-VOLs. You must assign the pool you are using
to the resource group where the P-VOL is assigned or to a resource group
where you can create Thin Image pairs.

For more information about resource groups, see the Provisioning Guide for
your storage system.

System option modes for Thin Image

To provide greater flexibility, the storage systems have additional operational
parameters called system option modes (SOMs) that allow you to tailor the
storage system to your unique operating requirements. The SOMs are set on
the service processor (SVP) by your service representative. Review the SOMs

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for your storage system, and work with your service representative to ensure
that the appropriate SOMs for your operational environment are configured
on your storage system.

The following table lists and describes the SOMs that apply to Thin Image.
For a complete list of SOMs, see the System Administrator Guide for your
storage system.

Note: The SOM information might have changed since this document was
published. Contact customer support for the latest SOM information.

Table 1 System option modes for Thin Image

Mode

471 Thin Image Since the SIM-RCs generated when the Thin Image pool

749 Dynamic

896 Dynamic

Category Description Default MCU/RCU

usage rate exceeds the threshold value can be resolved by
users, these SIM-RCs are not reported to the maintenance
personnel. This mode is used to report these SIM-RCs to
maintenance personnel.

The SIM-RCs reported by setting the mode to ON are:
601xxx (Pool utilization threshold exceeded), 603000 (SM
space warning).

Mode 471 = ON: These SIM-RCs are reported to
maintenance personnel.

Mode 471 = OFF: These SIM-RCs are not reported to
maintenance personnel.

Note: Set this mode to ON when it is required to inform
maintenance personnel of these SIM-RCs.

This mode disables the HDP Rebalance function and the HDT

Provisioning

Dynamic
Provisioning for
Mainframe

Dynamic Tiering

Dynamic Tiering
for Mainframe

Thin Image

Provisioning

Dynamic
Provisioning for
Mainframe

Tier relocation function which allow the drives of all ECC
Groups in the pool to share the load.

Mode 749 = ON: The HDP Rebalance function and the HDT
Tier relocation function are disabled.

Mode 749 = OFF (default): The HDP Rebalance function
and the HDT Tier relocation function are enabled.

Notes:

1. This mode is applied when no change in performance

characteristic is desired.

2. When a pool is newly installed, the load may be
concentrated on the installed pool volumes.

3. When 0 data discarding is executed, load may be
unbalanced among pool volumes.

4. Pool VOL deletion while the mode is set to ON fails. To
delete pool VOLs, set the mode to OFF.

This mode enables or disables the background format
function performed on an unformatted area of a DP/DT/TI
pool.

For information regarding operating conditions, see the
Provisioning Guide for your storage system.

OFF -

OFF -

ON (VSP
G1x00
and VSP
F1500)

-

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Mode Category Description Default MCU/RCU

Dynamic Tiering

Dynamic Tiering
for Mainframe

VSP G1x00 and VSP F1500:

Mode 896 = ON (default): The background format function
is enabled.

OFF (VSP
Gx00 and
VSP Fx00)

Thin Image

1093 Dynamic

Provisioning

Dynamic Tiering

Thin Image

Mode 896 = OFF: The background format function is
disabled.

VSP Gx00 models and VSP Fx00 models:

Mode 896 = ON: The background format function is
disabled.

Mode 896 = OFF (default): The background format
function is enabled.

Notes:

1. This mode is applied when a customer requires the

background format for a DP/DT/TI pool in the
environment where new page allocation (in the case
that system files are created from a host for newly
created multiple DP-VOLs, for example) frequently
occurs and the write performance degrades because of
an increase in write pending rate.

2. When the background format function is enabled,
because up to 42 MB/s of ECCG performance is used,
local copy performance may degrade by about 10%.
Therefore, confirm whether the 10% performance
degradation is acceptable or not before enabling the
function.

3. When a Dynamic Provisioning VOL on an external
storage system, which is used as an external VOL, is
used as a pool VOL, if the external pool on the external
storage side becomes full due to the background
format, the external VOL may be blocked.
If the external pool capacity is smaller than the external
VOL capacity (Dynamic Provisioning VOL of external
storage system), do not enable the background format
function.

4. If the background format function is disabled by
changing the mode setting, the format progress is
initialized and the entire area becomes unformatted.

5. The background format for FMC drives is not disabled.
When FMC drives are used, use SOM 1093.

This mode is used to disable background unmap during
microcode downgrade from a version that supports pool
reduction rate correction to a version that does not support
the function.

Mode 1093 = ON: Background unmap cannot work.

OFF -

Mode 1093 = OFF (default): Background unmap can work.

Note: This mode is applied when downgrading microcode

from a version that supports pool reduction rate correction to
a version that does not support the function is disabled.

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Acronyms and abbreviations for VSP family storage system software applications used in this guide

This user guide uses the following acronyms and abbreviations for software
names.

• FCv2: Compatible FlashCopy® V2

• FCSE: Hitachi Compatible FlashCopy

• GAD: global-active device

• SI: ShadowImage

• SIz: ShadowImage for Mainframe

• TC: TrueCopy

• TCz: TrueCopy for Mainframe

• HTI: Hitachi Thin Image

• UR: Universal Replicator

• URz: Universal Replicator for Mainframe

®

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2

Thin Image system and planning

requirements

Before you start working with Thin Image, review the requirements
associated with licensed capacity, shared memory, volume, data pool, and for
general planning and mangement tasks.

Thin Image system requirements

□

Thin Image planning requirements

□

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Thin Image system requirements

Before you install, uninstall, configure and use Thin Image, review the
requirements for the storage system, licensing, volumes, data pools,
consistency groups and snapshot groups.

The following is a list of requirements for completing HTI tasks:

• You have a VSP family storage system with P-VOL and S-VOLs.

• HTI and HDP, which run on HDvM - SN computers, are installed.
HDP accesses data in pool-VOLs by way of V-VOLs. It can handle data in

open-system servers such as UNIX and PC servers.

• The hardware and microcode (or firmware) is configured and set up.

• You have used HDvM - SN to install the license key for HDP.
For more information about license keys and installing HDvM - SN and

HDP, see the System Administrator Guide for your storage system.

Installing Thin Image

Use this procedure to install Thin Image.

Procedure

1. Install Dynamic Provisioning.

Note: Dynamic Provisioning is prerequisite software for Thin

Image.

2. Install Thin Image.

Uninstalling Thin Image

Use this procedure to remove Thin Image from HDvM - SN.

Procedure

1. Delete the Thin Image pairs.

2. Delete all pools.

3. Remove Thin Image.

Related tasks

• Deleting Thin Image pairs on page 146

•

Deleting pools on page 187

Thin Image licensed capacity requirements

Thin Image requires licensed capacity for the Thin Image P-VOLs and pools.

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Thin Image uses a portion of the Dynamic Provisioning licensed capacity for
its pool capacity. Make sure you have enough Dynamic Provisioning licensed
capacity to run both HDP and Thin Image.

The following table shows the Thin Image volumes and capacity calculated as
the Thin Image usage. The total amount of these values must not exceed the
Thin Image licensed capacity.

Intended volumes

Software application Volume type

HTI P-VOL Normal volume The volume capacity

Pool-VOL Normal volume

Notes:

1. For the volume with capacity saving enabled, HTI licensed capacity is the data capacity before

saving.

2. Not including the volumes of pools which are not in use by Thin Image pairs.

Normal volume or

DP-VOL

DP-VOL The pool capacity used by

Intended capacity

the volume

• Thin Image pool: volume
capacity

• DP pool: volume
capacity

1

2

For more information about licenses, see the System Administrator Guide for
your storage system.

Related concepts

• VSP family software applications for Thin Image on page 25

Thin Image shared memory requirements

Thin Image requires dedicated shared memory (SM) for the Thin Image pair
management area.

The Thin Image pair management area is an area used to store information
for associating Thin Image pairs that is automatically created when you
install shared memory.

Additional shared memory is required when the total capacity of all pools
exceeds certain values. The following table shows the shared memory
requirements for VSP G1000 and G1500, and VSP F1500:

Capacity of all pools

Under 1.1 PB None*

From 1.1 PB to 3.4 PB 8 GB

From 3.4 PB to 7.9 PB 24 GB

From 7.9 PB to 12.3 PB 40 GB

Capacity required for additional SM

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Capacity of all pools Capacity required for additional SM

*You must expand SM when pool capacity is more than 1.1 PB.

For VSP Gx00 models and VSP Fx00 models, additional shared memory is
required when the total capacity of all pools exceeds the following values:

• VSP G200: 0.12 PB

• VSP G400, G600, G800, VSP F400, F600, F800: 0.2 PB

For more information about capacity available for additional shared memory
for VSP Gx00 models and VSP Fx00 models, see the hardware guide for your
storage system.

You can reduce or remove shared memory if the pools for Dynamic
Provisioning, Dynamic Tiering, active flash, and Thin Image have been
deleted. When creating cascaded pairs or clone pairs, you must add shared
memory:

• For VSP G1000, G1500, and VSP F1500: 64KLDEV Extension

• For VSP Gx00 models and VSP Fx00 models: Extension1

For more information about how to expand, reduce, or remove shared
memory, contact customer support.

Related concepts

•

Switching off the power supply on page 193

Related tasks

• Deleting pools on page 187

Thin Image volume requirements

Thin Image requires three types of volumes.

The following types of volumes are required:

• P-VOLs

• S-VOLs

• Pool-VOLs

The following table lists the requirements for Thin Image P-VOLs.

Please note that "Pool VOLs" refers to Thin Image pool volumes. For
information about DP pool volumes, see the Provisioning Guide for your
storage system.

Item

Requirement

Volume type Logical volumes (LDEVs).

You cannot specify the following volumes as HTI P-VOLs:

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Item Requirement

• Pool-VOLs

• HTI S-VOLs

• Volumes that belong to parity groups for which
accelerated compression is enabled

For more information about creating pairs using other
software applications, see

other software applications on page 42.

Emulation type OPEN-V

Volume limit 32,768

For more information about the maximum number of HTI
pairs, see Thin Image planning requirements on page 76.

Path definitions Required. (Not required for cascaded pairs and pairs with the

clone attribute)

Volume capacity limit 256 TB

Maximum number of cascades 64 layers (L64). For each primary volume, 1,024 S-VOLs can

be used.

Maximum number of clones

1,024. When storing snapshot data, this number includes the
number of snapshots.

Sharing Thin Image volumes with

The following table lists the requirements for Thin Image S-VOLs.

An S-VOL must be specified if you want to create a Thin Image pair with an
S-VOL. If you create a Thin Image pair without an S-VOL, an S-VOL need not
be specified.

Item

Volume type Thin Image V-VOL (V-VOLs of provisioning type Snapshot) or

DP-VOL.

You cannot specify the following volumes as HTI S-VOLs:

• Volumes that are already used as S-VOLs.

• Volumes that other software applications are using for
pairs or migration plans.

• Deduplication system data volume.

Emulation type OPEN-V

Maximum number of volumes 32,768

For more information about the maximum number of HTI
pairs, see Thin Image planning requirements on page 76.

Path definitions Required. (Not required for cascaded pairs and pairs with the

clone attribute)

Requirement

The following table lists the requirements for Thin Image pool-VOLs.

Item

Volume type Logical volumes (LDEVs).

Requirement

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Item Requirement

To maintain performance levels, use the following configurations:

• Place normal volumes and pool-VOLs in separate parity groups (see

Thin Image licensed capacity requirements on page 68).

• Ensure that pool-VOLs consist of LDEVs from more than one parity
group.

You cannot specify the following volumes as HTI pool-VOLs:

• LDEV whose LDEV status is other than Normal, Correction Access, or
Copying.

• Volumes that are already being used as HTI P-VOL or S-VOLs.

• Volumes that are already contained in HTI, HDP, HDT, or active flash
pools.

• Volumes used as migration plans or pair volumes for another
product.

• Volumes for which you have used the Data Retention Utility to set
Read Only, Protect, or S-VOL Disable attributes.

• (VSP G1000, G1500, and VSP F1500) Cache Residency Manager
volumes.

• Command device volumes.

• GAD volumes with the reservation attribute.

• GAD volumes for quorum disks.

• External volumes with the Data Direct Mapping attribute.

• DP-VOLs with the Data Direct Mapping attribute.

Note: The following restrictions apply to volumes used in the same data
pool:

• Volumes must be in the same resource group.

• External pool-VOLs must have the same cache mode, either enabled
or disabled.

• When using both internal and external volumes, the external
volumes must have cache mode enabled.

Emulation type

RAID level All RAID levels are supported.

Data drive type You can use SAS and SSD.*

OPEN-V

Regardless of the type of the volume (internal volume or external
volume), you can use pool-VOLs with different drive types in the same
pool. For best performance, use pool-VOLs with the same drive type in
the same pool.

For more information about data drive type, see

drive type priority on page 106.

CLPR Registering pool-VOLs to Cache Logical Partition Numbers (CLPRs) in

pools:

You can register pool-VOLs assigned to different CLPRs in a pool (see

Workflow for registering virtual volumes on page 107).

Changing CLPRs:

You can change CLPRs in the parity group belonging to the pool-VOL. In
this case, regardless of the CLPR in the pool-VOL, the CLPR ID in the
parity must be the same as that of the P-VOL that you are using.

Pool limit 1,024

Volume capacity 8 GB to 4 TB

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Pool creation and data

Item Requirement

Path definition Define only needed paths to a volume so that you can specify the

volume as a pool-VOL.

*SSD contains SSD (SLC, MLC) and FMD.

Thin Image data pool requirements

The following table lists the requirements for Thin Image data pools.

For information about DP pools, see the Provisioning Guide for your storage
system.

Item

Pool capacity Calculate the pool capacity (see Calculating and assigning pool

capacity on page 80).

The following are the maximum total capacity of pools in a
storage system:

• VSP G200: 3.5 PB (if Extension1 or Extension2 is added in
the shared memory capacity).

• VSP G400, G600, G800 and VSP F400, F600, F800: 6.5 PB
(if Extension1, Extension2, Extension3, or Extension4 is
added in the shared memory capacity).

• Hitachi Virtual Storage Platform G1000 and G1500, and
Virtual Storage Platform F1500: 12.3 PB (if DP/HDT/Active
Flash/TI Extension1, DP/HDT/Active Flash/TI Extension2, or
DP/HDT/Active Flash/TI Extension3 is added in the shared
memory capacity).

The maximum pool capacity that can be used for each primary
volume is 768 TB.

Pool-VOL limit per pool 1,024

Note: You cannot assign a volume that is already assigned to a
pool as a pool-VOL to another pool.

Pool limit per storage system

• VSP G200, VSP G400, G600: 64
Pool IDs are assigned from 0 to 63.

• VSP G800, VSP G1000, G1500, and VSP F1500: 128
Pool IDs are assigned from 0 to 127.

Requirement

This can include HDP (including HDT and active flash), HDPz
(including HDTz and active flash for mainframe), and HTI pool
types.

Increasing capacity Dynamically increase the pool-VOL capacity. To do this, increase

the capacity for at least one parity group.

Decreasing pool capacity Use the following workflow to decrease pool capacity:

1. Delete the pool-VOLs (see Decreasing pool capacity on

page 177).

2. Reconfigure the pool (see Creating Thin Image data pools

on page 101).

Deleting pools The pool is not used by an HTI pair.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Item Requirement

For more information about deleting pools, see Deleting pools

on page 187.

Data pool warning threshold Value: Warning Threshold

Range: 20 - 95%, in 1% increments.

Default: 80%

Note: If you exceed the data pool warning threshold, a warning
is issued through a service information message (SIM) and an
SNMP trap reporting excessive pool usage.

For more information:

• About editing the data pool warning threshold, see

the data pool warning threshold on page 181.

• About checking alerts and checking the details of a SIM, see
the System Administrator Guide for your storage system.

• About SNMP traps, see the Hitachi SNMP Agent User Guide.

Thin Image consistency group requirements

The attributes of Thin Image consistency groups, such as the pair limit and
pair type, have usage requirements. Review these requirements before
creating consistency groups.

Editing

Item

Consistency group ID Value: 0 to 2,047

With SI, SIz, and HTI, you can create up to 2,048 consistency
groups in a VSP G1000, G1500, and VSP F1500 storage system.

Manual assignment of a consistency group ID to an HTI pair
using the paircreate command:

• Specify a consistency group ID from 0 to 255.

Automatic assignment of a consistency group ID to an HTI pair
using the paircreate or raidcom add snapshot commands:

• Using the paircreate command, if a number is not specified,
an unassigned number from 0 to 255 is automatically
assigned.

• Using the raidcom add snapshot command, if a number is
not specified, an unassigned number from 0 to 2,047 is
automatically assigned.

Consistency group ID is displayed in the following windows:

• Consistency Groups tab in Local Replication window.

• Consistency Group Properties window.

Pair limit 8,192 pairs per consistency group.

Pair type

SI, SIz, and Thin Image pairs cannot be contained in a single
consistency group. For Thin Image consistency groups, only Thin
Image pairs can be defined in a group.

1

Requirement

2

Snapshot and cloned pairs cannot be contained in a single
consistency group.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

Item Requirement

Notes:

1. Thin Image assigns a number in ascending order from 0 to 255.

2. ShadowImage uses numbers from 0 to 127. Because of this, Thin Image assigns an

unassigned number from 128 to 2,047 first. If there is no unassigned number from 128 to
2,047, then Thin Image assigns an unassigned number from 0 to 127.

For microcode versions earlier than 80-05-0X-XX/XX, Thin Image assigns a number from 0 to
2,047. Therefore, if a consistency group was created in an earlier version, a number from 0 to 127
may be used as its consistency group ID even if there is an unassigned number from 128 to 2,047.

Consistency group restrictions:

• Thin Image pairs that share P-VOLs or are in higher and lower layers of a
snapshot tree cannot be defined in the same consistency group. If they are
defined in the same consistency group, the raidcom add snapshot
command is rejected.

• Do not place pairs that are not in consistency groups, in a group defined
by the CCI configuration definition file. If these pairs are in the same
group, the pairsplit command may terminate and the snapshot data
may not be the P-VOL data generated when VSP G1000 and G1500, and
VSP F1500 received the pairsplit command.

• Only one consistency group can be specified for a group defined in the CCI
configuration definition file.

• When a pair where a consistency group is specified and already created, if
you specify another consistency group to create a pair, the pair is added to
the same consistency group.

• To specify multiple consistency groups, use the CCI configuration definition
file to define the same number of groups as the consistency groups you
want to specify.

Thin Image snapshot group requirements

The following table outlines the requirements for working with Thin Image
snapshot groups.

Item

Name Character limit: 32.

You can change snapshot group names using CCI commands. For
details about CCI commands, see CCI command reference for

Thin Image on page 211 and the Command Control Interface

Installation and Configuration Guide.

Group and HTI pair limit

Pair type Snapshot and cloned pairs cannot be contained in a single

Restrictions for Snapshot groups:

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

• Snapshot groups per storage system: 2,048.

• HTI pairs per snapshot group: 8,192.

snapshot group.

Requirement

• When creating a Thin Image cascaded pair with the CTG mode specified
using CCI, a volume belonging to the snapshot group and the following
volumes cannot be contained in the same snapshot group:

○ The P-VOL or S-VOL of a volume belonging to the snapshot group
○ A volume that uses the same P-VOL with a different MU number as the

volume belonging to the snapshot group

Thin Image planning requirements

You must calculate the number of Thin Image pairs you can create.

When you create Thin Image pairs for a P-VOL for the first time, the number
of pairs that you can create in a storage system depends on several
variables.

• The number of Thin Image pairs that you can create based on the number
of available pair tables.

• The snapshot estimated manageable capacity.

• The number of cache management devices that you must make available.

The smallest of the three calculations is the maximum number of Thin Image
pairs that you can create in the storage system.

When you create Thin Image pairs again, you only need to know the number
of pair tables to calculate the number of pairs that you can create. You do not
need to know the snapshot estimated manageable capacity or the number of
cache management devices.

If you have multiple P-VOLs, calculate the number of Thin Image pairs that
you can create for each P-VOL in the storage system.

Calculating the number of Thin Image pairs based on pair tables

Pair tables contain information that is required to manage HTI pairs. Each
HTI pair requires at least one pair table.

The number of HTI pairs that you will need is maximum-number-of-existing-
pair-tables - number-of-existing-pairs.

Maximum number of pair tables:

• VSP Gx00 models and VSP Fx00 models: 102,400

• VSP G1000, G1500, and VSP F1500: 1,048,575

To view the number of existing HTI pairs, see

summary information on page 157.

Viewing local replication

Calculating Thin Image pairs based on the snapshot estimated manageable capacity

You can calculate the number of HTI pairs you can create based on the
snapshot estimated manageable capacity.

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To view the snapshot estimated manageable capacity, see Viewing local

replication summary information on page 157.

Calculate the number of HTI pairs that you can create using the following
formulas, where SM refers to shared memory:

Number of HTI pairs that you can create =
Snapshot estimated manageable capacity / Snapshot management
capacity in a P-VOL

Snapshot estimated manageable capacity in a P-VOL [GB] =
(P-VOL capacity of HTI pairs [TB] / 2.6) * 3,024 + (168 * 2
(consumed shared memory [GB]))

Related tasks

•

Viewing the list of primary volumes on page 159

Calculating Thin Image pairs based on cache management devices

Cache management devices are the unit for controlling the cache in
association with logical volumes (LDEVs). They are required to perform HTI
tasks, such as creating HTI pairs for a volume.

To view the number of cache management devices, see

of cache management devices on page 170.

Use the following formula to calculate the number of HTI pairs that you can
create based on the number of cache management devices:

Number of HTI pairs that you can create =
Number of cache management devices / ceil (the P-VOL capacity of
HTI pairs [TB]) / 2.6)

Related concepts

•

Calculating the number of remaining cache management devices on

page 207

Viewing the number

Calculating the number of cache management devices

You can calculate the number of cache management devices you must
reserve to initially create a Thin Image pair for a volume.

Use the following formula:

Number of cache management devices that you must reserve =
ceil (Size of P-VOL [TB] / 2.6)

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If the amount of pool usage for the P-VOL exceeds 70 percent of the total
capacity of the cache management devices reserved for the P-VOL, you must
reserve another cache management device. You can reserve a maximum of
256 cache management devices for each P-VOL.

Calculating the Thin Image pair capacity for DP pools

When creating a DP pool, you can set the maximum reserved V-VOL capacity
against the pool capacity. For details about the maximum reserved capacity,
see the Provisioning Guide for Open Systems.

When storing snapshot data in a DP pool, set the maximum reserved V-VOL
capacity against theDP pool by calculating the V-VOL capacity of a Thin
Image pair (Thin Image pair capacity) using the following formula:

Thin Image pair capacity = Σ↑(P-VOL capacity (MB)
× Number of pairs × 2 ÷ 42 (MB))↑ × 42 (MB) + Σ↑(P-VOL capacity
(MB) × Number of pairs
× 2 ÷ 2,921,688 (MB))↑ × 175,434 (MB)

Decimal places of the value enclosed by arrows (↑value↑) are rounded up.

As for Number of pairs in the formula, allocated pages are not released if you
delete pairs. Because of this, use the maximum number of TI pairs you want
to create in the applicable snapshot tree as Number of pairs instead of using
the number of pairs currently created in the applicable snapshot tree.

If a pair or snapshot data is deleted, allocated pages are not released. As a
result, if you delete pairs or snapshot data, the TI pair capacity is not
decreased. To decrease the TI pair capacity by releasing allocated pages, you
must delete all TI pairs and snapshot data created in the applicable snapshot
tree.

The following example illustrates how the TI pair capacity is calculated.

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When you create three TI pairs using the 500 GB (500 x 1024 MB) volume as
the P-VOL, the TI pair capacity is calculated as follows:

↑(500 × 1,024 × 3 × 2 ÷ 42)↑ × 42 + ↑(500 × 1,024 × 3 × 2 ÷
2,921,688)↑
× 175,434 ＝ 3,422,874 (MB)

Afterward, if you delete two pairs, the maximum number of TI pairs you can
create in the applicable snapshot tree is the same: The TI pair capacity does
not change.

Also, if you you split pairs twice, the maximum number of TI pairs you can
create in the snapshot tree is the same, and the TI pair capacity remains
unchanged.

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Thin Image cache management device requirements

The following table shows the cache management device requirements for
performing Thin Image tasks.

For information about DP tasks, see the Provisioning Guide for your storage
system.

Task

Initially create an HTI pool.

Create a volume. 1

Create a P-VOL. 256

Initially create an HTI pair for a volume.
(VSP G1000, G1500, and VSP F1500)

(VSP G1000, G1500, and VSP F1500) You can manage up to 65,280 cache
management devices in a storage system.

Calculating and assigning pool capacity

Use these formulas to calculate and assign pool capacity.

Use the following formula to calculate the capacity of the snapshot data that
you can store in the Thin Image pool:

Number of cache management devices

required

• VSP G200: 3,840

• VSP G400, G600 and VSP F400, F600:
7,936

• VSP G800 and VSP F800: 32,512

• VSP G1000, G1500, and VSP F1500:
8,192*

*HTI assigns 4,096 of the 8,192 devices that
are available.

4,097

Capacity of the snapshot data that you can store in the pool =
Total capacity of pool-VOLs in the pool - Capacity of V-VOL
management areas

The capacity of V-VOL management areas is 3% of the pool capacity.

Use the following formula to calculate the capacity of the snapshot data that
you can store in the DP pool:

Capacity of the snapshot data that you can store in the pool =
Total capacity of pool-VOLs in the pool - (Capacity of pool VOLs
used by DP-VOLs +
Capacity of V-VOL management areas)

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Use the following formula to calculate the pool capacity:

Capacity of the pool [MB] =
Total number of pages * 42 - 4200

Use the following formula to calculate the total number of pages:

Total number of pages =
Sigma (floor (floor (pool-VOL number of blocks / 512) / 168))
for each pool-VOL

floor( ): Truncates the value calculated from the formula in parentheses after
the decimal point.

Estimate pool-VOL capacity in multiples of 42 MB. Specifying a pool-VOL
capacity in other multiples less than 42 MB truncates the fraction.

If you install HDP/HDT/HTI Extension in the shared memory, the available
pool capacity per P-VOL is 768 TB, and the total capacity of all pools depends
on the storage system model:

• VSP G200: 3.5 PB (when Extension1 and Extension2 are added to the
shared memory capacity)

• VSP G400, G600, G800 and VSP F400, F600, F800: 6.5 PB (when
Extension1, Extension2, Extension3, and Extension4 are added to the
shared memory capacity)

• VSP G1000 and G1500, and VSP F1500: 12.3 PB

Related references

•

Thin Image shared memory requirements on page 69

Resolving insufficient pool capacity

Make sure you have sufficient pool capacity. If the pool capacity is
insufficient, the storage system can suspend Thin Image pairs ("PSUE"
status).

Note: When the setting, Suspend TI pairs when depletion threshold is
exceeded, is set to Yes for a DP pool, the status of TI pairs using the pool
might change to PSUE if the depletion threshold is exceeded. When it is set
to No for a TI pool or a DP pool, the status of TI pairs using the pool might
change to PSUE if the pool becomes full.

Procedure

1. Estimate the capacity of snapshot data to be copied to the pool.

If the capacity of snapshot data to be copied to the pool varies hour by
hour, ensure that the largest capacity is your pool capacity.

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

2. Assign the pool capacity based on the estimate.

Pool capacity calculations

You can calculate the required pool capacity by estimating the capacity of
snapshot data to be copied.

Use the following formula:

Capacity of snapshot data to be copied =
Capacity of data written to the same area in the P-VOL during
the period from when snapshot data is stored to when the
snapshot data is deleted

Although the pool capacity is decided according to the estimation, if the pool
capacity exceeds the threshold, address the issue.

If multiple snapshot data are stored, the data may be shared in a pool. In
this case, you can release Thin Image pairs, but the snapshot data cannot be
deleted from the pool. If you release all Thin Image pairs that have snapshot
data containing the shared data, the snapshot data are also deleted from the
pool.

Creating a backup of data

You can create a backup of data using Thin Image. When creating a backup
from the S-VOL after storing snapshot data, the target for the backup is only
the areas where the snapshot data is stored. Therefore, you can create a
backup copy even if the pool capacity is small.

During creation of a backup copy, a significant amount of data is read from
the secondary volume. This may increase the accesses to the primary volume
and degrade the host I/O performance.

Procedure

1. Store the snapshot data, or clone pairs.

2. Use an S-VOL.

Related tasks

•

Splitting Thin Image pairs to store snapshot data on page 136

Universal Volume Manager and external volumes used as pool-VOLs

You can use Universal Volume Manager (UVM) to connect a VSP family
storage system to other storage systems.

In UVM, a VSP family storage system is referred to as a local storage system,
and the other storage systems are referred to as external storage systems.
With UVM installed, you can use external and internal volumes as pool-VOLs.
Volumes in local storage systems are referred to as internal volumes, and
volumes in external storage systems are referred to as external volumes.

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Note: Using external volumes increases the likelihood of a failure, and
disaster recovery is more complex and challenging. Using multiple external
volumes as pool-VOLs in a pool increases the likelihood of the pool being
blocked.

To minimize the adverse effects of failure, use only one pool per external
storage system. An external pool-VOL that is blocked due to a failure blocks
the pool. You must restore blocked pools.

For more information about external storage systems and disaster recovery
methods for external volumes, see the Hitachi Universal Volume Manager
User Guide.

Simultaneous processing of multiple Thin Image pair tasks

Some Thin Image pair task operations are processed in the background after
the requested task is accepted. The total number of instances of each pair
task that can be simultaneously processed in a storage system is limited by
the number of MP blades (or units) in the storage system.

Note: The terms "blade" and "unit" refer to the same hardware on different
VSP storage systems. The term "blade" is used for VSP G1000, G1500, and
VSP F1500, and the term "unit" is used for VSP G200, G400, G600, G800.

For each of the following pair tasks, the number of simultaneous instances
processed in the background is equal to the total number of MP blades (or
units) in the storage system:

• Creating pairs.

• Restoring pairs.

• Deleting snapshot data and deleting pairs.

When you execute additional pair task operations above these limits, the
tasks are processed in the order requested.

Related tasks

•

Creating Thin Image pairs using Device Manager - Storage Navigator on

page 130

• Restoring Thin Image pairs on page 141

•

Resynchronizing Thin Image pairs on page 144

• Deleting Thin Image pairs on page 146

Pair operations when pairs are cascaded

The following table explains pair operations according to the pair status. The
status of pair B is SMPL.

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Pair
type

Pair A
status

Operation for pair B

Snapsh
ot /

Pair with snapshot attribute

Create Split Resync Restore Create Split Delete

Pair with clone
attribute

clone
attribut
e
commo
n

With the
snapshot
attribute

With the
clone
attribute

Y: Operation successful.

COPY(PD)N N N N N N YN

PAIR Y N N N Y N YN

PSUS Y N N N Y N YN

COPY(RS)N N N N N N YN

COPY(RS

-R)

PSUE N N N N N N YN

SMPL(PD)N N N N N N YN

COPY(PD)N N N N N N YN

PAIR Y N N N Y N YN

PSUS(SP) Y N N N Y N YN

PSUE N N N N N N YN

SMPL(PD)N N N N N N YN

N N N N N N YN

YN: Operation not performed, process terminated.

N: Process terminated abnormally.

The following table explains operations of cascaded pair B when pair B has
the snapshot attribute, and its pair status is COPY(PD).

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Pair
Type

Pair A
status

Operation for pair B

Snapsh
ot /

Pair with snapshot attribute

Create Split Resync Restore Create Split Delete

Pair with clone
attribute

clone
attribut
e
commo
n

With the
snapshot
attribute

With the
clone
attribute

Y: Operation successful.

COPY(PD)N/A N/A N/A N/A N/A N/A N/A

PAIR YN N YN YN N N N

PSUS YN N YN YN N N N

COPY(RS)YN N YN YN N N N

COPY(RS

-R)

PSUE YN N YN YN N N N

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

COPY(PD)YN N YN YN N N N

PAIR YN N YN YN N N N

PSUS(SP) YN N YN YN N N N

PSUE YN N YN YN N N N

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

YN N YN YN N N N

YN: Operation not performed, process terminated.

N: Process terminated abnormally.

The following table explains operations of cascaded pair A when pair B has
the snapshot attribute, and its pair status is COPY(PD).

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Pair
Type

Pair A
status

Operation for pair A

Snapsh
ot /

Pair with snapshot attribute

Create Split Resync Restore Create Split Delete

Pair with clone
attribute

clone
attribut
e
commo
n

With the
snapshot
attribute

With the
clone
attribute

Y: Operation successful.

COPY(PD)N/A N/A N/A N/A N/A N/A N/A

PAIR N Y YN YN N N N

PSUS N YN Y Y N N N

COPY(RS)YN N YN YN N N N

COPY(RS

-R)

PSUE YN N YN YN N N N

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

COPY(PD)N N N N N N N

PAIR N N N N N Y N

PSUS(SP) N N N N N YN N

PSUE N N N N N N N

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

YN N YN YN N N N

YN: Operation not performed, process terminated.

N: Process terminated abnormally.

The following table explains operations of cascaded pair B when pair B has
the clone attribute, and its pair status is COPY(PD).

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Pair
Type

Pair A
status

Operation for pair B

Snapsh
ot /

Pair with snapshot attribute

Create Split Resync Restore Create Split Delete

Pair with clone
attribute

clone
attribut
e
commo
n

With the
snapshot
attribute

With the
clone
attribute

Y: Operation successful.

COPY(PD)N/A N/A N/A N/A N/A N/A N/A

PAIR N N N N N N Y

PSUS N N N N N N Y

COPY(RS)N N N N N N Y

COPY(RS

-R)

PSUE N N N N N N Y

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

COPY(PD)N N N N N N Y

PAIR N N N N N N Y

PSUS(SP) N N N N N N Y

PSUE N N N N N N Y

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

N N N N N N Y

N: Process terminated abnormally.

The following table explains operations of cascaded pair A when pair B has
the clone attribute, and its pair status is COPY(PD).

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Pair
type

Pair A
status

Operation for pair A

Snapsh
ot /

Pair with snapshot attribute

Create Split Resync Restore Create Split Delete

Pair with clone
attribute

clone
attribut
e
commo
n

With the
snapshot
attribute

With the
clone
attribute

Y: Operation successful.

COPY(PD)N/A N/A N/A N/A N/A N/A N/A

PAIR N Y YN YN N N N

PSUS N YN Y Y N N N

COPY(RS)YN N YN YN N N N

COPY(RS

-R)

PSUE N N N N N N N

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

COPY(PD)N N N N N N N

PAIR N N N N N Y N

PSUS(SP) N N N N N YN N

PSUE N N N N N N N

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

YN N YN YN N N N

YN: Operation not performed, process terminated.

N: Process terminated abnormally.

The following table explains operations of cascaded pair B when pair B has
the snapshot attribute and its pair status is PAIR.

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Pair
type

Pair A
status

Operation for pair B

Snapsh
ot /

Pair with snapshot attribute

Create Split Resync Restore Create Split Delete

Pair with clone
attribute

clone
attribut
e
commo
n

With the
snapshot
attribute

With the
clone
attribute

Y: Operation successful.

COPY(PD)N N YN YN N N Y

PAIR N N YN YN N N Y

PSUS N Y YN YN N N Y

COPY(RS)N N YN YN N N Y

COPY(RS

-R)

PSUE N/A N/A N/A N/A N/A N/A N/A

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

COPY(PD)N N YN YN N N Y

PAIR N N YN YN N N Y

PSUS(SP) N Y YN YN N N Y

PSUE N/A N/A N/A N/A N/A N/A N/A

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

N N YN YN N N Y

YN: Operation not performed, process terminated.

N: Process terminated abnormally.

The following table explains operations of cascaded pair A when pair B has
the snapshot attribute, and its pair status is PAIR.

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Pair
type

Pair A
status

Operation for pair A

Snapsh
ot /

Pair with snapshot attribute

Create Split Resync Restore Create Split Delete

Pair with clone
attribute

clone
attribut
e
commo
n

With the
snapshot
attribute

With the
clone
attribute

Y: Operation successful.

COPY(PD)YN N YN YN N N N

PAIR N Y YN YN N N N

PSUS N YN Y Y N N N

COPY(RS)YN N YN YN N N N

COPY(RS

-R)

PSUE N/A N/A N/A N/A N/A N/A N/A

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

COPY(PD)N N N N N N N

PAIR N N N N N Y N

PSUS(SP) N N N N N YN N

PSUE N/A N/A N/A N/A N/A N/A N/A

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

YN N YN YN N N N

YN: Operation not performed, process terminated.

N: Process terminated abnormally.

The following table explains operations of cascaded pair B when pair B has
the clone attribute and its pair status is PAIR.

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Pair
type

Pair A
status

Operation for pair B

Snapsh
ot /

Pair with snapshot attribute

Create Split Resync Restore Create Split Delete

Pair with clone
attribute

clone
attribut
e
commo
n

With the
snapshot
attribute

With the
clone
attribute

Y: Operation successful.

COPY(PD)N N N N N N Y

PAIR N N N N N N Y

PSUS N N N N N Y Y

COPY(RS)N N N N N N Y

COPY(RS

-R)

PSUE N/A N/A N/A N/A N/A N/A N/A

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

COPY(PD)N N N N N N Y

PAIR N N N N N Y Y

PSUS(SP) N N N N N Y Y

PSUE N/A N/A N/A N/A N/A N/A N/A

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

N N N N N N Y

YN: Operation not performed, process terminated.

N: Process terminated abnormally.

The following table explains operations of cascaded pair A when pair B has
the clone attribute, and its pair status is PAIR.

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Pair
type

Pair A
status

Operation for pair A

Snapsh
ot /

Pair with snapshot attribute

Create Split Resync Restore Create Split Delete

Pair with clone
attribute

clone
attribut
e
commo
n

With the
snapshot
attribute

With the
clone
attribute

Y: Operation successful.

COPY(PD)YN N YN YN N N N

PAIR N Y YN YN N N N

PSUS N YN Y Y N N N

COPY(RS)YN N YN YN N N N

COPY(RS

-R)

PSUE N/A N/A N/A N/A N/A N/A N/A

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

COPY(PD)N N N N N N N

PAIR N N N N N Y N

PSUS(SP) N N N N N YN N

PSUE N/A N/A N/A N/A N/A N/A N/A

SMPL(PD)N/A N/A N/A N/A N/A N/A N/A

YN N YN YN N N N

YN: Operation not performed, process terminated.

N: Process terminated abnormally.

The following table explains operations of cascaded pair B when the status of
pair B is not SMPL, COPY(PD), and PAIR.

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Pair
type

Pair A
status

Pair B
status

Operation for pair B

Pair with snapshot attribute

Pair with clone
attribute

Snaps
hot /
clone
attribu
te
comm
on

With
the
snapsho
t
attribut
e

With
the
clone
attribut
e

Create Split Resync

Restor
e

Create Split Delete

PSUS PSUS 1N YN Y Y N N Y

PSUS COPY(R

1

S)

PSUS COPY(R

S-R)

YN N YN YN N N N

YN N YN YN N N N

1

PSUS PSUE 1N N Y N N N Y

PSUS SMPL(P

1

D)

PSUS PSUS(S

2

P)

PSUS(SP)PSUS(S

2

P)

N N N N N N YN

N N N N N N Y

N N N N N N Y

PSUS(SP)PSUE 2N N N N N N Y

PSUS(SP)SMPL(P

2

D)

N N N N N N YN

PSUS(SP)PSUS 1N YN Y Y N N N

Y: Operation successful.

YN: Operation not performed, process terminated.

N: Process terminated abnormally.

Notes

1. Pair B has snapshot attribute.

2. Pair B has clone attribute.

The following table explains operations of cascaded pair A when the status of
pair B is not SMPL, COPY(PD), and PAIR.

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Pair
type

Pair A
status

Pair B
status

Operation for pair A

Pair with snapshot attribute

Pair with clone
attribute

Snaps
hot /
clone
attribu
te
comm
on

With
the
snapsho
t
attribut
e

With
the
clone
attribut
e

Create Split Resync

PSUS PSUS 1N YN N N N N N

PSUS COPY(R

PSUS COPY(R

PSUS PSUE 1N YN N N N N N

PSUS SMPL(P

PSUS PSUS(S

PSUS(SP)PSUS(S

PSUS(SP)PSUE 2N N N N N YN N

PSUS(SP)SMPL(P

PSUS(SP)PSUS 1N N N N N YN N

1

S)

S-R)

1

D)

2

P)

2

P)

2

D)

N YN N N N N N

N YN N N N N N

1

N YN N N N N N

N YN N N N N N

N N N N N YN N

N N N N N YN N

Restor
e

Create Split Delete

Y: Operation successful.

YN: Operation not performed, process terminated.

N: Process terminated abnormally.

Notes

1. Pair B has snapshot attribute.

2. Pair B has clone attribute.

Pair operations when pairs are not cascaded

The following table explains pair operations according to the pair status.

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Operation for pair A

Snapsh
ot /

Pair
type

N/A SMPL Y N N N Y N YN

With the
snapshot
attribute

Pair A
status

COPY(PD)YN N YN YN N N N

PAIR N Y YN YN N N Y

PSUS N YN Y Y N N Y

COPY(RS)YN N YN YN N N N

Pair with snapshot attribute

Create Split Resync Restore Create Split Delete

Pair with clone
attribute

clone
attribut
e
commo
n

COPY(RS

-R)

PSUE N N Y N N N Y

SMPL(PD)N N N N N N YN

With the
clone
attribute

Y: Operation successful.

YN: Operation not performed, process terminated.

N: Process terminated abnormally.

COPY(PD)N N N N N N Y

PAIR N N N N N Y Y

PSUS(SP) N N N N N YN Y

PSUE N N N N N N Y

SMPL(PD)N N N N N N YN

YN N YN YN N N N

Pair operations when a P-VOL is shared by multiple S-VOLs

The following table explains pair operations according to the pair status.

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Pair
type

Pair
status
of other
S-VOLs

Operation for the target S-VOL

Snapsh
ot /

Pair with snapshot attribute

Create Split Resync Restore Create Split Delete

Pair with clone
attribute

clone
attribut
e
commo
n

With the
snapshot
attribute

With the
clone
attribute

Y: Operation successful.

COPY(PD)Y Y Y Y Y Y Y

PAIR Y Y Y Y Y Y Y

PSUS Y Y Y Y Y Y Y

COPY(RS)Y Y Y Y Y Y Y

COPY(RS

-R)

PSUE Y Y Y Y Y Y Y

SMPL(PD)Y Y Y Y Y Y Y

COPY(PD)Y Y Y Y Y Y Y

PAIR Y Y Y Y Y Y Y

PSUS(SP) Y Y Y Y Y Y Y

PSUE Y Y Y Y Y Y Y

SMPL(PD)Y Y Y Y Y Y Y

Y N Y N Y N Y

N: Process terminated abnormally.

Differences between Thin Image and ShadowImage

Item Thin Image (HTI) ShadowImage (SI)

P-VOL physical failures such as
hard disks.

P-VOL logical failures such as
data update errors or viruses.

Capacity required for backup. Less capacity is required for

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Hitachi Thin Image User Guide for Hitachi Virtual Storage Platform G Series and F Series

P-VOL data cannot be
guaranteed.

P-VOL data can be recovered
using the S-VOL.

backups because only

P-VOL data can be recovered
using the S-VOL.

P-VOL data can be recovered
using the S-VOL.

More capacity is required for
backup because all data in the
P-VOL is retained.

Item Thin Image (HTI) ShadowImage (SI)

differential data of the P-VOL is
retained.

Impact on P-VOL performance
when accessing backed up
data.

Notes:

1. For snapshot pairs. When a cloned pair is created, all data in the P-VOL is retained and more

capacity is required for backup.

2. For snapshot pairs. When a cloned pair is created, the P-VOL and the S-VOL can be separated
and the P-VOL performance is not affected.

P-VOL performance is affected
because data in the P-VOL is
shared.

1

P-VOL performance is not

2

affected because the P-VOL and
the S-VOL can be disconnected.

Recommended usage

To maintain backed up data for long periods, save it on magnetic tapes or
other media. For temporary backups use HTI or SI. When backing up data to
magnetic tapes use SI. To reduce the capacity necessary for backups use
HTI, but note that this affects P-VOL performance.

Use SI to minimize the impact from P-VOL physical failures. If you need four
or more generations of backups, use both SI and HTI as shown in the
following figure.

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Use HTI to minimize P-VOL logical failures.

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3

Configuring Thin Image

You can create data pools, LDEVs, and apply settings of the command device
to configure Thin Image.

Prerequisites for configuring Thin Image

□

Workflow for configuring Thin Image

□

Workflow for registering virtual volumes

□

Overview of using CCI to run commands through in-band connections

□

Changing system options that affect Thin Image performance

□

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Prerequisites for configuring Thin Image

Before you perform Thin Image configuration tasks, complete the following
tasks:

• Install a sufficient amount of shared memory.
For more information about installing shared memory, contact customer

support.

• Create a V-VOL management area in the shared memory. This area is
automatically created when you install additional shared memory.

Workflow for configuring Thin Image

Use this workflow to configure Thin Image.

The following image shows the configuration tasks workflow and the workflow
for creating and managing Thin Image pairs.

Steps for configuring Thin Image:

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