Hitachi AMS2100, AMS2300, AMS2500 User Manual

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Hitachi AMS 2000 Family Copy-on-Write

SnapShot User Guide

AST

IND

INKS

Document organization Release notes and readme Getting help Table of Contents

MK-97DF8124-26

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mechanical, including photocopying and recording, or stored in a database or retrieval system for any purpose without the express written permission of Hitachi, Ltd. and Hitachi Data Systems Corporation (hereinafter referred to as “Hitachi”).

Hitachi, Ltd. and Hitachi Data Systems reserve the right to make changes to this document at any time without notice and assume no responsibility for its use. Hitachi, Ltd. and Hitachi Data Systems products and services can only be ordered under the terms and conditions of Hitachi Data Systems' applicable agreements.

All of the features described in this document may not be currently available. Refer to the most recent product announcement or contact your local Hitachi Data Systems sales office for information on feature and product availability.

Notice: Hitachi Data Systems products and services can be ordered only under the terms and conditions of Hitachi Data Systems’ applicable agreements. The use of Hitachi Data Systems products is governed by the terms of your agreements with Hitachi Data Systems.

Hitachi is a registered trademark of Hitachi, Ltd. in the United States and other countries. Hitachi Data Systems is a registered trademark and service mark of Hitachi in the United States and other countries.

All other trademarks, service marks, and company names are properties of their respective owners.

Export authorization is required for the AMS 2000 Data At Rest Encryption

• Import/Use regulations may restrict export of the AMS2000 SED to certain countries

• China – AMS2000 is eligible for import but the License Key and SED may not be sent to China

• France – Import pending completion of registration formalities

• Hong Kong – Import pending completion of registration formalities

• Israel – Import pending completion of registration formalities

• Russia – Import pending completion of notification formalities

• Distribution Centers – IDC, EDC and ADC cleared for exports

Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

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Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

Intended audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .x

Product version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .x

Release notes and readme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .x

Product Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .x

Document revision level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

Changes in this revision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii

Document organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii

Document conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xiii

Convention for storage capacity values. . . . . . . . . . . . . . . . . . . . . . . . . . . . .xiv

Related documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xiv

Getting help. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xx

Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xx

1 SnapShot overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Copy-on-Write SnapShot software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Hardware and software configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

How SnapShot works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

Volume pairs — P-VOLs and V-VOLs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

Data pools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

Consistency group (CTG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

Differential Management LUs (DMLU) . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

LU Ownership of P-VOLs and data pools . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

Interfaces for performing SnapShot operations . . . . . . . . . . . . . . . . . . . . . . 1-8

Cascade connection of SnapShot with Simple DR. . . . . . . . . . . . . . . . . . . . . 1-9

Cascade connection of SnapShot with Simple DR P-VOL . . . . . . . . . . . . . 1-10

Cascade connection of SnapShot with Simple DR S-VOL . . . . . . . . . . . . . 1-11

V-VOLs number of SnapShot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11

Cascade connection of SnapShot with TrueCopy . . . . . . . . . . . . . . . . . . . . 1-12

Cascade restrictions with SnapShot P-VOL . . . . . . . . . . . . . . . . . . . . . . . 1-12

LU shared with P-VOL on SnapShot and P-VOL on TrueCopy . . . . . . . . 1-13

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Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

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One LU used for P-VOL on SnapShot and S-VOL on TrueCopy. . . . . . . .1-13

V-VOLs number of SnapShot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-14

Cascade restrictions with SnapShot V-VOL . . . . . . . . . . . . . . . . . . . . . . .1-14

Configuration restrictions on the Cascade of TrueCopy with SnapShot . . . .1-16

Cascade restrictions with SnapShot Data Pool . . . . . . . . . . . . . . . . . . . . .1-16

Cache memory reconfiguration cautions . . . . . . . . . . . . . . . . . . . . . . .1-16

Cascade connection of SnapShot with ShadowImage . . . . . . . . . . . . . . . . .1-19

Cascade connection with P-VOL of ShadowImage . . . . . . . . . . . . . . . . . .1-22

Restriction when performing restoration . . . . . . . . . . . . . . . . . . . . . . .1-22

Performance when cascading the P-VOL of SnapShot and ShadowImage1-22

Cascade restrictions with S-VOL of ShadowImage . . . . . . . . . . . . . . . . . .1-24

Pair Operation Restrictions when Cascading SnapShot with ShadowImage.1-27

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-29

Simultaneous Cascading Restrictions with ShadowImage P-VOL and S-VOL1-30

Cascade Restrictions of TrueCopy with ShadowImage and SnapShot. . . . .1-31

2 Planning and design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1

The plan and design workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2

Assessing business needs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2

Copy frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2

Selecting a reasonable time between Snapshots . . . . . . . . . . . . . . . . . .2-3

Establishing how long a copy is held (copy lifespan). . . . . . . . . . . . . . . . . .2-3

Lifespan based on backup requirements . . . . . . . . . . . . . . . . . . . . . . . .2-3

Lifespan based on business uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4

Establishing the number of V-VOLs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4

Establishing data pool size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5

Measuring workload data, sizing the data pool. . . . . . . . . . . . . . . . . . . . . .2-5

Rule-of-thumb calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-9

Requirements and recommendations for SnapShot Logical Units . . . . . . . . .2-10

RAID configuration for LUs assigned to SnapShot . . . . . . . . . . . . . . . . . .2-10

Operating system considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-13

Identifying P-VOL and V-VOL LUs on Windows . . . . . . . . . . . . . . . . . . . .2-13

LU mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-14

Cluster and path switching software. . . . . . . . . . . . . . . . . . . . . . . . . . . .2-14

Microsoft Cluster Server (MSCS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-14

AIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-14

Veritas Volume Manager (VxVM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-14

Windows 2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-14

Windows Server and SnapShot configuration. . . . . . . . . . . . . . . . . . . . . .2-15

Linux and LVM configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-16

Tru64 UNIX and SnapShot configuration. . . . . . . . . . . . . . . . . . . . . . . . .2-16

Concurrent use of Cache Partition Manager. . . . . . . . . . . . . . . . . . . . . . .2-16

VMWare and SnapShot configuration . . . . . . . . . . . . . . . . . . . . . . . . . . .2-16

Concurrent use of Dynamic Provisioning . . . . . . . . . . . . . . . . . . . . . . . . .2-18

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User data area of cache memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-21

Windows 2000/Windows Server and Dynamic Disk. . . . . . . . . . . . . . . . . .2-27

Limitations of Dirty Data Flush Number . . . . . . . . . . . . . . . . . . . . . . . . . .2-28

Formatting the DMLU in the Event of a Drive Failure. . . . . . . . . . . . . . . . .2-28

Cascading SnapShot with TrueCopy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-29

Cascading SnapShot with TrueCopy Extended Distance . . . . . . . . . . . . . . . .2-30

Maximum supported capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-31

SnapShot and TCE capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-32

. . . . . . . . . . . . . . .Maximum Supported Capacity of P-VOL and Data Pool2-34

No SnapShot-TCE cascade configuration . . . . . . . . . . . . . . . . . . . . . . .2-35

SnapShot-TCE cascade configuration. . . . . . . . . . . . . . . . . . . . . . . . . .2-36

SnapShot, TCE, ShadowImage concurrent capacity . . . . . . . . . . . . . . . . .2-37

Cache limitations on Data and Data Pool volumes . . . . . . . . . . . . . . . . . .2-39

3 System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1

System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

Displaying the hardware revision number . . . . . . . . . . . . . . . . . . . . . . . . 3-3

Supported platforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

4 Installing and enabling SnapShot . . . . . . . . . . . . . . . . . . . . . . . . .4-1

Important prerequisite information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Installing or uninstalling SnapShot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Enabling or disabling SnapShot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-11

5 Configuring SnapShot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1

Configuration workflow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Setting up the data pool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Setting up the Virtual Volume (V-VOL) (manual method) . . . . . . . . . . . . . . . 5-4

Setting up the Differential Management LU (DMLU). . . . . . . . . . . . . . . . . . . 5-5

Setting up the command device. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6

Setting the LU ownership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7

Setting the System Tuning Parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-8

Cascade configuration of SnapShot and ShawdowImage . . . . . . . . . . . . . . . 5-9

Pair Resynchronization and Releasing. . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-10

6 Using SnapShot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1

SnapShot replication workflow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

Back up your volume — creating a pair . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

Creating a pair using the Backup Wizard . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

Creating a pair using the Create Pair procedure . . . . . . . . . . . . . . . . . . . . 6-3

Updating the V-VOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5

Restoring the P-VOL from the V-VOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6

Use the V-VOL for tape backup, testing, reports, etc. . . . . . . . . . . . . . . . . . 6-7

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Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

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Tape backup recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-8

Restoring data from a tape backup. . . . . . . . . . . . . . . . . . . . . . . . . . . .6-9

Editing a pair, data pool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-10

Deleting pairs, V-VOLs, data pools, DMLU . . . . . . . . . . . . . . . . . . . . . . . . .6-10

7 Monitoring and maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-1

Monitoring SnapShot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-2

Monitoring pair status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-2

Monitoring data pool usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-4

Expanding data pool capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-4

Other methods for lowering data pool load . . . . . . . . . . . . . . . . . . . . . . . .7-4

8 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-1

Pair failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-2

Recovering from pair failure due to POOL FULL . . . . . . . . . . . . . . . . . . . . .8-2

Recovering from pair failure due to a hardware failure . . . . . . . . . . . . . . . .8-3

Data pool capacity exceeded . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-3

A Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

SnapShot specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-2

B Operations using CLI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

Installing and uninstalling SnapShot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-2

Important prerequisite information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-2

Installing SnapShot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-2

Uninstalling SnapShot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-6

Enabling or disabling SnapShot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-7

Operations for SnapShot configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . .B-10

Setting the DMLU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-10

Setting the POOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-11

Setting the V-VOL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-13

Setting the LU ownership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-13

Setting the System Tuning Parameter . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-14

Performing SnapShot operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-15

Creating SnapShot pairs using CLI . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-15

Updating SnapShot Logical Unit using CLI. . . . . . . . . . . . . . . . . . . . . . . .B-15

Restoring V-VOL to P-VOL using CLI. . . . . . . . . . . . . . . . . . . . . . . . . . . .B-16

Releasing SnapShot pairs using CLI . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-17

Changing pair information using CLI. . . . . . . . . . . . . . . . . . . . . . . . . . . .B-17

Creating multiple SnapShot pairs that belong to a group using CLI . . . . . .B-18

Sample back up script for Windows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-19

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C Operations using CCI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

Setting up CCI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

Setting the command device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

Setting LU Mapping information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3

Defining the configuration definition file . . . . . . . . . . . . . . . . . . . . . . . . . C-4

Setting the environment variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-8

Performing SnapShot operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-10

Confirming pair status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-10

Paircreate operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-11

Pair creation using a consistency group. . . . . . . . . . . . . . . . . . . . . . . C-12

Updating the V-VOL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-12

Restoring a V-VOL to the P-VOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-13

Releasing SnapShot pairs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-13

Pair, group name differences in CCI and Navigator 2. . . . . . . . . . . . . . . . . C-14

D Using SnapShot with Cache Partition Manager . . . . . . . . . . . . . D-1

SnapShot with Cache Partition Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . D-2

Glossary Index

Contents vii

Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

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viii Contents

Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

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Preface

This document provides instructions on assessing your snapshot requirements, designing an implementation to meet those requirements, and implementing and operating Copy-on-Write Snapshot software using the Storage Navigator 2 graphical user interface.

This preface includes the following information:

 Intended audience  Product version  Release notes and readme  Document revision level  Changes in this revision  Document organization  Document conventions  Convention for storage capacity values  Related documentation  Getting help

Preface ix

Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

Page 10

Intended audience

This document is intended for system administrators, Hitachi Data Systems representatives, and Authorized Service Providers who install, configure, and operate Hitachi Adaptable Modular System (AMS) 2000 family storage systems.

Product version

This document applies to Hitachi AMS 2000 Family firmware version 08D1/D or later.

Release notes and readme

Read the release notes and readme file before installing and using this product. They may contain requirements or restrictions that are not fully described in this document and updates or corrections to this document.

Product Abbreviations

Product Abbreviation

ShadowImage ShadowImage In-system Replication Snapshot Copy-on-Write Snapshot TrueCopy Remote TrueCopy Remote Replication TCE TrueCopy Extended Distance TCMD TrueCopy Modular Distributed Windows Server Windows Server 2003, Windows Server 2008,

and Windows Server 2012.

Product Full Name

x Preface

Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

Page 11

Document revision level

This section provides a history of the revision changes to this document.

Revision Date Description

MK-97DF8124-01 October 2008 Initial release. MK-97DF8124-02 December 2008 Revision 02, supersedes and replaces MK-97DF8124-01. MK-97DF8124-03 March 2009 Revision 03, supersedes and replaces MK-97DF8124-02. MK-97DF8124-04 June 2009 Revision 04, supersedes and replaces MK-97DF8124-03. MK-97DF8124-05 August 2009 Revision 05, supersedes and replaces MK-97DF8124-04. MK-97DF8124-06 November 2009 Revision 06, supersedes and replaces MK-97DF8124-05. MK-97DF8124-07 January 2010 Revision 07, supersedes and replaces MK-97DF8124-06. MK-97DF8124-08 April 2010 Revision 08, supersedes and replaces MK-97DF8124-07. MK-97DF8124-09 August 2010 Revision 09, supersedes and replaces MK-97DF8124-08. MK-97DF8124-10 September 2010 Revision 10, supersedes and replaces MK-97DF8124-09. MK-97DF8124-11 November 2010 Revision 11, supersedes and replaces MK-97DF8124-10. MK-97DF8124-12 December 2010 Revision 12, supersedes and replaces MK-97DF8124-11. MK-97DF8124-13 February 2011 Revision 13, supersedes and replaces MK-97DF8124-12. MK-97DF8124-14 May 2011 Revision 14, supersedes and replaces MK-97DF8124-13. MK-97DF8124-15 July 2011 Revision 15 supersedes and replaces MK-97DF8124-14. MK-97DF8124-16 August 2011 Revision 16 supersedes and replaces MK-97DF8124-15. MK-97DF8124-17 September 2011 Revision 17 supersedes and replaces MK-97DF8124-16. MK-97DF8124-18 March 2012 Revision 18 supersedes and replaces MK-97DF8124-17. MK-97DF8124-19 June 2012 Revision 19 supersedes and replaces MK-97DF8124-18. MK-97DF8124-20 December 2012 Revision 20 supersedes and replaces MK-97DF8124-19. MK-97DF8124-21 January 2013 Revision 21 supersedes and replaces MK-97DF8124-20. MK-97DF8124-22 May 2013 Revision 22 supersedes and replaces MK-97DF8124-21. MK-97DF8124-23 July 2013 Revision 23 supersedes and replaces MK-97DF8124-22. MK-97DF8124-24 December 2013 Revision 24 supersedes and replaces MK-97DF8124-23. MK-97DF8124-25 January 2015 Revision 25 supersedes and replaces MK-97DF8124-24. MK-97DF8124-26 January 2016 Revision 26 supersedes and replaces MK-97DF8124-25.

Preface xi

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Changes in this revision

The following information has been added for this release:

•Under Creating a pair using the Create Pair procedure on page 6-3, added the note after step 5.

•Under Creating SnapShot pairs using CLI on page B-15 and Paircreate

operation on page C-11, added the note preceding the procedure.

Document organization

Thumbnail descriptions of the chapters are provided in the following table. Click the chapter title in the first column to go to that chapter. The first page of every chapter or appendix contains links to the contents.

Chapter/Appendix

Title

Chapter 1, SnapShot overview

Chapter 2, Planning and design

Chapter 3, System requirements

Chapter 4, Installing and enabling SnapShot

Chapter 5, Configuring SnapShot

Chapter 6, Using SnapShot

Chapter 7, Monitoring and maintenance

Chapter 8, Troubleshooting

Appendix A, Specifications

Appendix B, Operations using CLI

Appendix C, Operations using CCI

Appendix D, Using SnapShot with Cache Partition Manager

Glossary Provides definitions for terms and acronyms found in this

Index Provides locations to specific information in this document.

Provides descriptions of SnapShot components and how they work together.

Provides detailed planning and design information.

Provides SnapShot requirements.

Provides instructions for installing SnapShot.

Provides configuration information.

Provides information and procedures for using SnapShot.

Provides monitoring and maintenance information.

Provides information for correcting system problems.

Provides SnapShot specifications.

Provides Navigator 2 Command Line Interface instructions for configuring and using SnapShot.

Provides detailed Command Control Interface instructions for configuring and using SnapShot.

Provides information for using SnapShot with Cache Partition Manager.

document.

Description

xii Preface

Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

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Document conventions

This document uses the following symbols to draw attention to important safety and operational information.

Symbol Meaning Description

Tip Tips provide helpful information, guidelines, or suggestions for

Note Notes emphasize or supplement important points of the main

Caution Cautions indicate that failure to take a specified action could

The following typographic conventions are used in this document.

Convention Description

Bold Indicates text on a window, other than the window title, including

menus, menu options, buttons, fields, and labels. Example: Click OK.

Italic Indicates a variable, which is a placeholder for actual text provided

by the user or system. Example: copy source-file target-file. Note: Angled brackets (< >) are also used to indicate variables.

screen/code

< > angled brackets

[ ] square brackets

{ } braces

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

underline Indicates the default value. Example: [ a

Indicates text that is displayed on screen or entered by the user. Example: # pairdisplay -g oradb

Indicates a variable, which is a placeholder for actual text provided by the user or system. Example: # pairdisplay -g <group> Note: Italic font is also used to indicate variables.

Indicates optional values. Example: [ a | b ] indicates that you can choose a, b, or nothing.

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

arguments. Examples: [ a | b ] indicates that you can choose a, b, or nothing. { a | b } indicates that you must choose either a or b.

performing tasks more effectively.

text.

result in damage to the software or hardware.

| b ]

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Convention for storage capacity values

Physical storage capacity values (e.g., disk drive capacity) are calculated based on the following values:

Physical capacity unit Value

1 KB 1,000 bytes 1 MB 1,000 KB or 1,000 1 GB 1,000 MB or 1,0003 bytes 1 TB 1,000 GB or 1,0004 bytes 1 PB 1,000 TB or 1,0005 bytes 1 EB 1,000 PB or 1,000

Logical storage capacity values (e.g. , logical device capacity) are calculated based on the following values:

Logical capacity unit Value

1 block 512 bytes 1 KB 1,024 (210) bytes 1 MB 1,024 KB or 1024 1 GB 1,024 MB or 10243 bytes 1 TB 1,024 GB or 10244 bytes 1 PB 1,024 TB or 1024 1 EB 1,024 PB or 10246 bytes

bytes

Getting help

If you need to contact the Hitachi Data Systems support center, please provide as much information about the problem as possible, including:

• The circumstances surrounding the error or failure.

• The exact content of any messages displayed on the host systems.

• The exact content of any messages displayed on Storage Navigator Modular 2.

• The Storage Navigator Modular 2 configuration information. This information is used by service personnel for troubleshooting purposes.

The Hitachi Data Systems customer support staff is available 24 hours a day , seven da ys a week. If you need technical support, please log on to the Hitachi Data Systems Portal for contact information: https://portal.hds.com

Comments

Please send us your comments on this document to

doc.comments@hds.com

and refer to specific sections and paragraphs whenever possible. Thank you! (All comments become the property of Hitachi Data Systems.)

. Include the document title, number , and revision,

xx Preface

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SnapShot overview

Copy-on-Write SnapShot creates virtual copies of data volumes within the Hitachi Adaptable Modular Storage (AMS) array. These copies can be used for recovery from logical errors. They are identical to the original volume at the point in time they were taken.

This guide provides instructions for planning and designing, configuring and testing, and using and monitoring SnapShot. In this chapter, see the following:

 Copy-on-Write SnapShot software  Hardware and software configuration  How SnapShot works  Interfaces for performing SnapShot operations  Cascade connection of SnapShot with Simple DR  Cascade connection of SnapShot with ShadowImage

NOTE: “SnapShot” refers to Copy-on-Write SnapShot software. A “snapshot” refers to a copy of the primary volume (P-VOL).

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Copy-on-Write SnapShot software

Hitachi’s Copy-on-Write Snapshot software creates virtual backup copies of any data volume within the AMS array with minimal impact to host service or performance levels. These snapshots are suitable for immediate use in decision support, software testing and development, data backup, or rapid recovery operations.

SnapShot minimizes disruption of planned or unplanned outages for any application that cannot tolerate downtime for any reason or that requires non-disruptive sharing of data. Since each snapshot captures only the changes to the original data volume, the amount of storage space required for each Copy-on-Write Snapshot is significantly smaller than the original data volume.

The most probable types of target applications for Copy-on-Write Snapshot are:

• Database copies for decision support/database inquiries

• Non-disruptive backups from a Snapshot secondary volume

• Periodic point-in-time disk copies for rapid restores in the event of a corrupted data volume

Hardware and software configuration

A typical SnapShot hardware configur ation includes an AMS arr ay, a host connected to the storage system, and management software to configure and manage SnapShot. The host is connected to the storage system using fibre channel or iSCSI connections. The management software is connected to the storage system via a management LAN.

SnapShot volumes include primary data volumes (P-VOLs) belonging to the same consistency group, secondary volumes referred to as virtual volumes (V-VOLs), data pool, a differential management logical unit (DMLU), and command device. These elements are explained in this chapter.

The SnapShot system is operated using Hitachi Storage Navigator Modular 2 (Navigator 2) graphical user interface (GUI), Navigator 2 Command-Line interface (CLI), and Hitachi Command Control Interface (CCI).

Figure 1-1 shows the SnapShot configuration.

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•

Figure 1-1: SnapShot functional component

The following sections describe how these components work together.

How SnapShot works

SnapShot creates a virtual duplicate volume of another volume. This volume “pair” is created when you:

• Select a volume that you want to replicate

• Identify another volume that will contain the copy

• Associate the primary and secondary volumes

• Create a snapshot of primary volume data in the virtual (secondary) volume.

Once a snapshot is made, it remains unchanged until a new snapshot instruction is issued. At that time, the new image replaces the previous image.

Volume pairs — P-VOLs and V-VOLs

A volume pair is a relationship established by SnapShot between two volumes. A pair consists of a production volume, which contains the original data and is called the primary volume (P-VOL), and from 1 to 32 virtual volumes (V-VO Ls), which contain virtual copies of the PVOL. The P-VOL and its V-VOL(s) are located in the same array.

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Data pools

To maintain the snapshot image of the P-VOL when new data is written to the P-VOL, SnapShot copies data that is being replaced to the data pool. V-VOL pointers in cache memory are updated to reference the original data's new location in the data pool. Figure 1-

2 illustrates SnapShot volumes and data pool interaction.

A V-VOL provides a virtual image of the P-VOL at the time of the snapshot. Unlike the P-VOL, which contains actual data, the V -VOL is made up of pointers to the data in the P-VOL, and to original data that has been changed in the P-VOL since the last snapshot and which has been copied to the data pool.

V-VOL’s are set up with LUs that are the same size as the related PVOL. This capacity is not actually used and remains available as free storage capacity. This V-VOL sizing requirement (must be equal to the P-VOL), is necessary for SnapShot and array logic. Also, V-VOL pointers to data in the data pool and P- VOL actually reside in cache memory . Because of this, part of your array’s cache is reserved for SnapShot when it is enabled. (See Maximum supported capacity

on page 2-31 and Appendix D, Using SnapShot with Cache Partition Manager.)

The data pool holds data from the P-VOL that is being replaced. After a snapshot is taken, the V-VOL maintains pointers to P-VOL

data. If changes occur, before the updated block is written to the PVOL, the data that is being replaced is first copied to the data pool. The V-VOL pointer to this block is updated to the new address in the data pool. Thus, the V-VOL maintains the point-in-time image of the P-VOL, until the next snapshot is taken.

A data pool can be shared by multiple SnapShot pairs. The data pool’s function in the SnapShot process is illustrated in

Figure 1-2.

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Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

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•

Figure 1-2: V-VOL Maintains SnapShot Data

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Page 26

Consistency group (CTG)

Application data often spans more than one volume. With SnapShot, it is possible to manage operations spanning multiple volumes as a single group. In a “consistency group” (CTG), all primary logical volumes are treated as a single entity.

Managing SnapShot primary volumes as a consistency group allows multiple operations to be performed on grouped volumes concurrently. Write order is guaranteed across application logical volumes, since snapshots can be taken at the same time.

Differential Management LUs (DMLU)

The DMLU is an exclusive volume used for storing SnapShot information when the array system is powered down. The DMLU is treated the same as other volumes in the storage system, but is hidden from a host. The DMLU requires user setup. See Setting up

the Differential Management LU (DMLU) on page 5-5 for details.

LU Ownership of P-VOLs and data pools

The load balancing function is not applied to the LUs specified as a SnapShot pair.

The ownership of the LU specified in the S-VOl of the SnapShot pair is the same as the ownership of the LU specified in the data pool. This ownership change operates regardless of the setting status of load balancing.

For example, if creating a SnapShot pair by specifying the LU whose ownership is controller 0 as a P-VOL and assigned the LU whose ownership is controller 1 as a data pool, the ownership of the LU specified in the P-VOL is changed to controller 1.

If two or more SnapShot pairs share the same data pool, the ownerships of all the pairs are biased toward the same controller and the load is concentrated. To diversify the load, create two or more data pools whose ownerships differ, and specify the data pool to be equal when creating a SnapShot pair.

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Figure 1-3: LU ownership

Furthermore, when adding LUs to increase the data pool capacity, if the ownership of the LU already allocated to the data pool and the ownership of the LU to be added have different controllers, the ownership of the LU to be added is changed to the ownership of the already allocated LU.

Figure 1-4: Adding LUs

If the ownership of a volume has been changed at pair creation, the ownership is not changed at pair deletion. After deleting a pair, set ownership again considering load balance.

Refer to Setting the LU ownership on page 5-7 or , for CLI, Setting the

LU ownership on page B-13 for more information.

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Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

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Interfaces for performing SnapShot operations

SnapShot can be operated using of the following interfaces:

• Navigator 2 GUI (Hitachi Storage Navigator Modular 2 Graphical User Interface) is a browser-based interface from which SnapShot can be setup, operated, and monitored. The GUI provides the simplest method for performing operations, requiring no previous experience. Scripting is not available.

• CLI (Hitachi Storage Navigator Modular 2 Command Line Interface), from which SnapShot can be setup and all basic pair operations can be performed—create, split, resynchronize, restore, swap, and delete. The GUI also provides thes e functionalities. CLI also has scripting capability.

• CCI (Hitachi Command Control Interface), used to display volume information and perform all copying and pair-managing operations. CCI provides a full scripting capability which can be used to automate replication operations. CCI requires more experience than the GUI or CLI. CCI is required on Windows 2000 Server for performing mount/unmount operations.

HDS recommends using the GUI to begin operations for new users with no experience with CLI or CCI. Users who are new to replication software but have CLI experience in managing arrays may want to continue using CLI, though the GUI is an option. The same recommendation applies to CCI users.

•

NOTE: Hitachi Replication Manager is used to manage and integrate Copyon-Write. It provides a GUI topology view of the SnapShot system, with monitoring, scheduling, and alert functions. For more information on purchasing Replication Manager, visit the Hitachi Data Systems website

http://www.hds.com/products/storage-software/hitachi-replicationmanager.html

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Cascade connection of SnapShot with Simple DR

Local

Disk Su bsyst em

Host

Simple DR

Remote

Disk Subsystem

P-VOL

V-VOL

SnapShot

Snap Shot

Read / Write

V-VOL

P-VOL

Cascade Connection

Local

Disk Su bsyst em

Host

Simple DR

Remote

Disk Subsystem

Snap Shot

Read / Write

V-VOL

P-VOL

Cascade Connection

Ca scade with a P-VOL of SnapS hot

Ca scade with a V-VOL of SnapS hot

P-VOL

V-VOL

SnapShot

P-VOL S-VOL

P-VOL

S-VOL

Volumes of SnapShot P-VOL can be cascaded with those of Simple DR, as shown in Figure 1-5. Cascading of SnapShot with Simple DR lowers performance, however.

•

Figure 1-5: Cascade Connection of SnapShot with Simple DR

The Simple DR pair can be cascaded only with the SnapShot P-VOL with the following restrictions placed on the cascade connection:

• Restoration of the SnapShot pair cascaded with the Simple DR P-VOL can be done only when the status of the Simple DR pair is Simplex, Split, or Pool Full.

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• When restoration of the SnapShot pair cascaded with the Simple DR S-VOL, it is required to make the status of the Simple DR pair Simplex or Split. The restoration can be done in the Takeover status, but it cannot be done when the status is Busy in which the S-VOL is being restored using the pool data.

• When the Simple DR S-VOL is in the Busy status in which it is being restored using the pool data, the Read/Write instruction cannot be issued to the SnapShot V-VOL cascaded with the Simple DR S-VOL.

Cascade connection of SnapShot with Simple DR P-VOL

LU Shared with P-VOL on SnapShot and P-VOL on Simple DR.

Table 1-1 shows whether a read/write from/to a P-VOL of SnapShot

on the local side is possible when a P-VOL of SnapShot and a P-VOL of Simple DR are the same LU.

•

Table 1-1: Read/Write Instructions to SnapShot P-VOL on the

Local Side (Simple DR)

SnapShot P-VOL

Simple DR P-VOL

Paired

Reverse

Synchronizing

Split Failure

Failure

(Restore)

Paired

Synchronizing

Split

Pool Full

Failure

+, R/W – +, R/W +, R/W – +, R/W – +, R/W +, R/W – +, R/W +, R/W +, R/W +, R/W ∆, R/W +, R/W +, R/W +, R/W +, R/W ∆, R/W +, R/W ∆, R/W +, R/W ∆, R/W ∆, R/W

+ indicates a possible case, – indicates an impossible case

∆ indicates a case where a pair operation causes an error (a case that

can occur as a result of a change of the pair status to Failure) R/W: Read/Write by a host is possible. R: Read by a host is possible but write is impossible. W: Write by a host is possible but read is impossible. R/W

•

NOTE: Failure in this table excludes a condition in which access of an LU is not allowed (for example, LU blockage).

: Read/Write by a host is impossible.

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Cascade connection of SnapShot with Simple DR S-VOL

One LU is used for a P-VOL on SnapShot and an S- VOL on Simple DR.

Table 1-2 shows whether a read/write from/to a P-VOL of SnapShot

on the remote side is possible when a P-VOL of SnapShot and an SVOL of Simple DR are the same LU.

•

Table 1-2: Read/Write Instruction to a SnapShot P-VOL on the

Remote Side (Simple DR)

SnapShot P-VOL

Simple DR S-VOL

Paired

Reverse

Synchronizing

Split Failure

Failure

(Restore)

Paired

Synchronizing

R/W

Split

Inconsistent

Takeover

Busy

Pool Full

+, R – +, R +, R – +, R – +, R +, R – +, R/W +, R/W +, R/W +, R/W ∆, R/W +, R – +, R +, R –

∆, R/W – ∆, R/W ∆, R/W –

+, R/W +, R/W +, R/W +, R/W ∆, R/W

∆, R/W – +, R/W +, R/W –

+, R – +, R ∆, R –

+ indicates a possible case, – indicates an impossible case

∆ indicates a case where a pair operation causes an error (a case that

•

NOTE: Failure in this table excludes a condition in which access of an LU is not allowed (for example, LU blockage).

: Read/Write by a host is impossible.

V-VOLs number of SnapShot

V-VOLs of up to 32 generations can be made even in the case where the P-VOL of SnapShot is cascaded with the P-VOL and S-VOL of Simple DR in the same way as in the case where no cascade connection is made.

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Cascade connection of SnapShot with TrueCopy

Local array

Host

TrueCopy

Remote array

P-VOL

V-VOL

SnapShot

Read/Write

V-VOL

P-VOL

Cascade Connection

Local array

Host

TrueCopy

Remote array

SnapShot

Read/Write

V-VOL

P-VOL

Cascade Connection



Cascade with a P-VOL of SnapShot



Cascade with a V-VOL of SnapShot

P-VOL

V-VOL

SnapShot

P-VOL S-VOL

P-VOL

S-VOL

Volumes of SnapShot can be cascaded with those of TrueCopy as shown in Figure 1-6. Because the cascade of SnapShot with TrueCopy lowers the performance, only use it when necessary.

•

Cascade restrictions with SnapShot P-VOL

Figure 1-6: Cascade Connection of SnapShot with TrueCopy

When restore using SnapShot is executed, TrueCopy must be in the Split status. If restore using SnapShot is executed in the Synchronizing status or Paired status of TrueCopy, the data in the LUs for P-VOL that are cascaded using T rueCopy on the local side and the remote side cannot be assured of equality.

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LU shared with P-VOL on SnapShot and P-VOL on TrueCopy

Table 1-3 shows whether a read/write to/from a SnapShot P-VOL on

the local side is possible or not in the case where a SnapShot P-VOL and a TrueCopy P-VOL are the same LU.

•

Table 1-3: Read/Write Instructions to SnapShot P-VOL on the

Local Side (TrueCopy)

SnapShot P-VOL

TrueCopy P-VOL

Paired

Synchronizing

R/W

Split

R/W

Failure

R/W

+ indicates a possible case, – indicates an impossible case

∆ indicates a case where a pair operation causes an error (a case that

•

: Read/Write by a host is impossible.

Paired

Synchronizing

Split Failure

(Restore)

+, R/W – +, R/W +, R/W – +, R/W – +, R/W +, R/W – +, R/W +, R/W +, R/W +, R/W ∆, R/W +, R – +, R +, R – +, R/W ∆, R/W +, R/W ∆, R/W ∆, R/W +, R – +, R ∆, R – +, R/W – +, R/W ∆, R/W –

Failure

(Restore)

NOTE: Failure in this table excludes a condition in which access of an LU is not allowed (for example, LU blockage).

One LU used for P-VOL on SnapShot and S-VOL on TrueCopy

Table 1-4 shows whether a read/write from/to a P-VOL of SnapShot

on the remote side is possible or not in the case where a P-VOL of SnapShot and an S-VOL of TrueCopy are the same LU.

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•

Table 1-4: Read/Write Instructions to SnapShot P-VOL on the

Remote Side (TrueCopy)

SnapShot P-VOL

TrueCopy S-VOL

Paired

Synchronizing

R/W

Split

Failure

Paired

+, R – +, R +, R – +, R – +, R +, R – +, R/W +, R/W +, R/W +, R/W ∆, R/W +, R – +, R +, R – +, R – +, R +, R –

Synchronizing

(Restore)

Split Failure

Failure

(Restore)

+ indicates a possible case, – indicates an impossible case

∆ indicates a case where a pair operation causes an error (a case that

•

NOTE: Failure in this table excludes a condition in which access of an LU is not allowed (for example, LU blockage).

: Read/Write by a host is impossible.

V-VOLs number of SnapShot

V-VOLs of up to 32 generations can be made even in the case where the SnapShot P-VOL is cascaded with the P-VOL and S-VOL of TrueCopy in the same way as in the case where no cascade connection is made.

Cascade restrictions with SnapShot V-VOL

The following explains the transition of statuses of TrueCopy and SnapShot pairs

About cascading of an LU of TrueCopy with a SnapShot V-VOL, it is supported only when the SnapShot V- VOL and a T rueCopy P-VOL are the same LU. Besides, operations of the SnapShot and TrueCopy pairs are restricted depending on statuses of the pairs.

When cascading volumes of T rueCopy with a SnapShot V-VOL, create a SnapShot pair first. When a TrueCopy pair is created earlier, split the TrueCopy pair once and create a pair using SnapShot.

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When changing a status of a SnapShot pair, a status of a TrueCopy pair must be Split or Failure. When changing a s tatus of a T rueCopy pair, a status of a SnapShot pair must be Split.

Table 1-5 shows whether a read/write to/from a SnapShot V-VOL on

the local side is possible or not in the case where a SnapShot V- VOL and a TrueCopy P-VOL are the same LU.

•

Table 1-5: Read/Write Instructions to SnapShot V-VOL on the

Local Side (TrueCopy)

SnapShot V-VOL

TrueCopy P-VOL

Paired

Synchronizing

R/W

Split

R/W

Failure

R/W

+ indicates a possible case, – indicates an impossible case

∆ indicates a case where a pair operation causes an error (a case that

•

: Read/Write by a host is impossible.

Paired

Synchronizing

(Restore)

Split Failure

Failure

(Restore)

–– +, R –– –– +, R ––

+, R/W +, R/W +, R/W ∆, R/W ∆, R/W +, R/W +, R/W +, R ∆, R/W ∆, R/W +, R/W +, R/W +, R/W ∆, R/W ∆, R/W +, R/W +, R/W +, R ∆, R/W ∆, R/W +, R/W +, R/W +, R/W ∆, R/W ∆, R/W

NOTE: Failure in this table excludes a condition in which access of an LU is not allowed (for example, LU blockage).

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Configuration restrictions on the Cascade of TrueCopy with SnapShot

V-VOL

TrueCopy

P-VOL

S-VOL

TrueCopy

S-VOL

P-VOL

V-VOL

TrueCopy

P-VOL

S-VOL

TrueCopy

S-VOL

P-VOL

V-VOL

V-V OL

TrueCopy

P-VOL

S-VOL

TrueCopy

S-VOL

P-VOL

Local array Remote array

Figure 1-7 shows an example of a configuration in which restrictions

are placed on the cascade of TrueCopy with SnapShot.

•

Cascade restrictions with SnapShot Data Pool

Cache memory reconfiguration cautions

Figure 1-7: Configuration restrictions on the Cascade of

TrueCopy with SnapShot

Neither TrueCopy/Simple DR pair nor ShadowImage pair can be created using a data pool.

When the firmware version of the array is 0897/A or more, the following cautions for cache memory reconfiguration processing in the installation, un-installation, or invalidation/validation operation occur.

• I/O processing performance The I/O performance, in case of the sequential write pattern,

deteriorates approximately 20% to 30% by releasing a part of the user data area in the cache memory and performing the memory

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reconfiguration of the management information stor age area for SnapShot. In other patterns, the I/O performance deteriorates less than 10%.

• Time-out for memory reconfiguration processing If the I/O inflow is large, data saving to the drives of the cache

data takes time and may time out in a internal processing time of 60 minutes. In this case, the processing can be continued by executing it again when the I/O inflow is small.

• Inhibiting the memory reconfiguration processing performance while executing other functions

In the following items, the memory reconfiguration processing is inhibited to increase the data amount to the cache. Perform the memory reconfiguration processing again after completing the operation of other functions or recovering the failure.

Other than master cache partition (partition 0 and partition 1) in use

- Cache partition in changing

- DP pool in optimization

- RAID group in growing

- LU ownership in changing

- Cache Residency LU in operation

- Remote path and/or pair of TrueCopy or TCE in operation

- SnapShot Logical Units or Data Pools in operation

- DMLU in operation

- Logical Unit in formatting

- Logical Unit in parity correction

- IP address for m aintenance or management in operation

- SSL information in operation

- A rray firmware in updating

- Power OFF of array in operation

- Spin-down or spin-up by Power Saving feature in operation

• Inhibiting the operation of other functions during memory reconfiguration

- When the memory reconfiguration processing fails on the

way due to the factors other then the time-out

- RAID group grown operation

- Replication Pair operation

- Dynamic Provisioning operation

- Cache Residency Manager setting operation

- Logical Unit formatting operation

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- Logical Unit parity correction operation

- Cache Partition Manager operation

- Modular Volume Migration operation

- A rray firmware updating operatio n

- Installing, uninstalling, enabling, or disabling of extra-cost option operation

- Logical Unit operation

- Logical Unit unifying operation

Table 1-6 shows the Memory Reconfiguring Statuses displayed on

Navigator 2.

Table 1-6: Memory Reconfiguring Statuses

Statuses Meaning

Normal Indicates that the memory reconfiguration processing

is completed normally.

Pending Indicates the status which is waiting for the memory

reconfiguration. Even if the memory reconfiguration instruction is executed and the message indicating the inoperable status is output, it is changed to this status because the instruction is received.

Reconfiguring(nn%) Indicates the status that the memory reconfiguration

is operating. (nn%) shows reconfiguring as a percent.

N/A Indicates that it is out of the memory reconfiguration

target.

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Table 1-6: Memory Reconfiguring Statuses

Statuses Meaning

Failed(Code-nn: error message)

Indicates the status that the memory reconfiguration failed because failures and others have occurred inside the array . Recover the status according to the following troubleshooting for each error code and each error message. If it still fails, call the Support Center.

Failed(Code-01: Time out)

Code-01 occurs when the access from the host is frequent or the amount of the unwritten data in the cache memory is large. Execute the memory reconfiguration operation again when the access from the host decreases.

Failed(Code-02: Failure of Reconfigure Memory)

Code-02 occurs when the drive restoration processing starts in the background. Execute the memory reconfiguration operation again after the drive restoration processing is completed.

Failed(Code-03: Failure of Reconfigure Memory)

Code-03 occurs when the copy of the management information in the cache memory fails. The controller replacement is required. Call the Support Center.

Failed(Code-04: Failure of Reconfigure Memory)

Code-04 occurs when the unwritten data in the cache memory cannot be saved to the drive. The restart of the array is required. Note: If the firmware version of the array is less than 0897/A, the memory reconfiguration without restart of the array is unsupported.

Cascade connection of SnapShot with ShadowImage

When the firmware version of the arra y is 08B0/A or more, volumes of SnapShot can be cascaded with those of ShadowImage as shown in Figure 1-8. However, the ShadowImage P-VOL and the SnapShot V-VOL can not be cascaded. Also , the ShadowImage S-VOL and the SnapShot V-VOL cannot be cascaded

SnapShot overview 1-19

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Figure 1-8: Cascade connection of SnapShot with ShadowImage

• LU Ownership When cascading SnapShot and ShadowImage, the LU Ownership is

the same as the owner controller which contains the data pool for SnapShot. If pairs are placed disproportionately in the controllers whose ownership is the same, the load is concentrated and the performance may deteriorate. Specify the ownership so that the the load can be diversified.

Also, the Loadbalancing feature does not apply to a ShadowImage pair that is cascaded with a SnapShot pair.

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Figure 1-9: LU ownership

SnapShot overview 1-21

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Cascade connection with P-VOL of ShadowImage

The SnapShot P-VOL can cascade the ShadowImage P-VOL. Operations of the SnapShot and ShadowImage pairs are restricted depending on statuses of the pairs.

Restriction when performing restoration

When performing restoration, the pair status of the pairs must be made different than those which make restoration Split. While the ShadowImage pair is executing restoration, the V-VOLs of the cascaded SnapShot cannot be Read/Write. When the restoration is completed, Read/Write from/to all the V-VOLs will be possible again.

Figure 1-10: While restoring ShadowImage, the SnapShot V-VOL

cannot be Read/Write

Performance when cascading the P-VOL of SnapShot and ShadowImage

In the configuration in which the P-VOL of SnapShot and the P-VOL of ShadowImage are cascaded, when SnapShot pair status is Split, and at the same time, ShadowImage pair status is any of Paired, Paired Internally Synchronizing, Synchronizing, and Split Pending, the host I/O performance for the P- VOL d eter i orat es . Use Shado wIm age in the Split status and, if needed, resynchronize the ShadowImage pair and acquire the backup.

Table 1-7 shows whether a read/write from/to a P-VOL of

ShadowImage is possible or not in the case where a P-VOL of SnapShot and a P-VOL of ShadowImage are the same LU.

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SnapShot P_VOL

Table 1-7: A Read/Write Instruction to a P-VOL of

Paired

(Includ-

ing

Paired

Inter-

naly

Syn-

chroniz-

ing)

Synchro-

nizing

ShadowImage

ShadowImage P_VOL

Reve

rse

Syn-

chro-

nizin

Split

Pend-

ing

Failure

(Restor

Failure (S_VOL Switch)

Paired

Reverse Synchro-

nizing

Split

Failure

Failure (Restore)



R/W

xx x



R/W



R/W

xx x∆



R/W



R/W



R/W

 indicates a possible case, x indicates an impossible case

x 

R/WR/W

x 

R/W



R/WR/WR/W



R/WR/WR/W

x ∆

R/W



R/W



R/W



R/W

∆

R/W

∆

R/W

∆ indicates a case where a pair operation causes an error (a case that

: Read/Write by a host is impossible.



R/W

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NOTE: When using SnapShot with ShadowImage

• Failure in this table excludes a condition in which access of an LU is not possible (for example, LU blockage).

• When one P-VOL configures a pair with one or more S-VOLs, decide which item is applied as the pair status of the P-VOL of the abovementioned ShadowImage with the following procedure:

- If all the pairs that the P-VOL concerned configures are in the

Split status, the item of Split is applied.

- If all the pairs that the P-VOL concerned configures are in the

Split status or the Failure status, the item of Split is applied. However, when including the pair that became Failure during restore, the items of Failure (Restore) are applied.

- If a pair in the Paired status, the Synchronizing status, or the

Reverse Synchronizing status is included in the pair that the PVOL concerned configures, the item of Paired, Synchronizing, and Reverse Synchronizing is applied, respectively.

Cascade restrictions with S-VOL of ShadowImage

Cascade of an LU of SnapShot with an S-VOL of ShadowImage, is supported only when the S-VOL of ShadowImage and a P-VOL of SnapShot are the same LU. Also, operations of the ShadowImage and SnapShot pairs are restricted depending on statuses of the pairs.

• Restriction of pair creation order. When cascading a P-VOL of

SnapShot with an S-VOL of ShadowImage, create a ShadowImage pair first. When a SnapShot pair is created earlier, delete the SnapShot pair once and create a pair using ShadowImage

• Restriction of Split Pending. When the ShadowImage pair

status is Split Pending, the SnapShot pair cannot be changed to the Split status. Execute it again after changing the ShadowImage pair status to other than Split Pending.

• Changing the SnapShot pair to Split while copying ShadowImage.

status while the ShadowImage pair status is Synchronizing or Paired Internally Synchronizing, the V-VOL data of SnapShot cannot be guaranteed. This is because the status where the background copy of ShadowImage is operating is determined as the V-VOL data of SnapShot.

When the SnapShot pair is changed to the Split

• Performing pair re-synchronization when the ShadowImage pair status is Failure.

synchronized when the ShadowImage pair status is Failure, all data is copied from the P-VOL to the S-VOL of ShadowImage. When the SnapShot pair status is Split, all data of the P-VOL of SnapShot is saved to the V-VOL. Be careful of the free capacity of the data pool used by the V-VOL.

If a pair is re

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• Performance at the time of cascading the P-VOL of SnapShot and the S-VOL of ShadowImage.

In the configuration in which the P-VOL of SnapShot and the S-VOL of ShadowImage are cascaded, when SnapShot pair status is Split, and the ShadowImage pair status is any of Paired, Paired Internally Synchronizing, Synchronizing, and Split Pending, the host I/O performance for the P-VOL of ShadowImage deteriorates. Use ShadowImage in the Split status and, if needed, resynchronize the ShadowImage pair and acquire the backup.

SnapShot P_VOL

Paired

Reverse

Synchronizing

Table 1-8

shows whether a read/write from/to an S-VOL of ShadowImage is possible when a P-VOL of SnapShot and an S-VOL of ShadowImage are the same LU.

Table 1-8: A Read/Write Instruction to a S-VOL of

ShadowImage

ShadowImage S-VOL

Paired

(Includi

Paired

Internal

Synchroni

zing

Synchro

nizing)



xx x



Reve

rse

Sync

hroni

zing



Split



R/WR/W

R/W

Pendin

xxxx

Failure



(Restor



R/W

Failure (S_VOL Switch)



R/W

Split

Failure

Failure (Restore)



xx x∆



 indicates a possible case, x indicates an impossible case



R/WR/W



R/WR/W

x ∆

R/W



R/W

∆

R/W

∆

R/W

∆ indicates a case where a pair operation causes an error (a case that

: Read/Write by a host is impossible.

SnapShot overview 1-25

R/W



R/W

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NOTE: When using SnapShot with ShadowImage

• Failure in this table excludes a condition in which access of an LU is not possible (for example, LU blockage).

• When one P-VOL configures a pair with one or more S-VOLs, decide which item is applied as the pair status of the P-VOL of the abovementioned ShadowImage with the following procedure:

- If all the pairs that the P-VOL concerned configures are in the

Split status, the item of Split is applied.

- If all the pairs that the P-VOL concerned configures are in the

Split status or the Failure status, the item of Split is applied. However, when including the pair that became Failure during restore, the items of Failure (Restore) are applied.

- If a pair in the Paired status, the Synchronizing status, or the

Reverse Synchronizing status is included in the pair that the PVOL concerned configures, the item of Paired, Synchronizing, and Reverse Synchronizing is applied, respectively.

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Pair Operation Restrictions when Cascading SnapShot with ShadowImage

Table 1-9 to Table 1-12 on page 1-29 shows pair status and operation

when cascading SnapShot with ShadowImage. The shaded areas in the tables indicate unworkable combinations.

Table 1-9: ShadowImage pair operation when LU shared

with P-VOL on ShadowImage and P-VOL on SnapShot (1)

SnapShot Pair Status

ShadowImage

Operation

Paired

Reverse

Synchronizing

Split Failure

Failure

(Restore)

Creating pairs

Splitting pairs

Re-synchronizing

pairs

Restoring pairs

Deleting pairs

 x  x

 

 x  x

xx  x

 

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SnapShot

Operation

Table 1-10: SnapShot pair operation when LU shared with

P-VOL on ShadowImage and P-VOL on SnapShot (2)

ShadowImage Pair Status

Paired

(Includi

Paired

Internal

Synchro

nizing)

Synchroni

zing

Reve

rse

Sync

hroni

zing

Split

Pendin

Failure

(Restor

Failure (S_VOL Switch)

qCreating pairs

Splitting pairs

Re-synchronizing

pairs

Restoring pairs

Deleting pairs

 xx

   x

 x   xx

xx x x  xx

  

Table 1-11: ShadowImage pair operation when LU shared

with S-VOL on ShadowImage and P-VOL on SnapShot (1)

SnapShot Pair Status

ShadowImage

Operation

Creating pairs

Splitting pairs

Paired

xx xxx

 

Reverse

Synchronizing

Split Failure

Failure

(Restore)

Re-synchronizing

 x  x

pairs

Restoring pairs

Deleting pairs

 x  x

 

1-28 SnapShot overview

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SnapShot

Operation

Table 1-12: SnapShot Pair Operation when LU Shared

with S-VOL on ShadowImage and P-VOL on SnapShot (2)

ShadowImage Pair Status

Paired

(Includi

Paired

Internal

Synchro

nizing)

Synchroni

zing

Reve

rse

Sync

hroni

zing

Split

Pendin

Failure

(Restor

Failure (S_VOL Switch)

Creating pairs

Splitting pairs

Re-synchronizing

pairs

Restoring pairs

Deleting pairs

 x 

xx x xxxx

  

SnapShot overview 1-29

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Simultaneous Cascading Restrictions with ShadowImage P-VOL and S-VOL

When the firmware version of the array is 08B0/A or more, the P-VOL and the S-VOL of ShadowImage can cascade SnapShot at the same time as shown in the status of Paired, Paired Internally Synchronizing, Synchronizing, or Split Pending and operating SnapShot in the Split status as is, the performance deteriorates significantly. Start the operation after advance verification

Figure 1-11. However, when operating ShadowImage in

Figure 1-11: Simultaneous Cascading Restrictions with

ShadowImage P-VOL and S-VOL

• LU Ownership. When cascading the P-VOL and the S-VOL of ShadowImage and SnapShot at the same time, if the owner controllers which the data pool for SnapShot specified at the time of SnapShot pair creation belongs are different, the pair creation is guarded. Execute the pair operation again by changing the ownership of the specified data pool for SnapShot or specifying the other data pool for SnapShot.

• Be careful when changing the LU ownership in the configuration in which the P-VOL and the S-VOL of ShadowImage and SnapShot are cascaded at the same time. Since the LU ownership change processing operates for all LUs in the cascaded configuration and all other SnapShot pairs using the data pool for SnapShot in the relevant pair configuration, the performance deterioration occurs at the time of execution. To change the ownership, perform it when the load of the array is low.

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Figure 1-12: Changing LU Ownership

Cascade Restrictions of TrueCopy with ShadowImage and SnapShot

When the firmware version of the array is 08B0/A or more, SnapShot can cascade ShadowImage and TrueCopy at the same time. However, since the performance may deteriorate, start the operation after advance verification.

• Cascade restrictions of TrueCopy S-VOL with SnapShot V-

In the configuration in which the P-VOL of ShadowImage and

Vol.

the P-VOL of SnapShot are cascaded as shown in at the same time, in the configuration in which the V-VOL of SnapShot and the S-VOL of TrueCopy are cascaded, when the TrueCopy pair status is Paired or Synchronizing, ShadowImage cannot be restored. Change the TrueCo py pair status to Split, and then execute it again.

Figure 1-13, and

Figure 1-13: Cascade restrictions of TrueCopy S-VOL with

SnapShot V-VOL

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Planning and design

A snapshot ensures that v olumes with bad or missing data can be restored. With Copy-on-Write, you create copies of your production data that can be used for backup and other uses.

Creating a copy system that fully supports business continuity is best done when SnapShot is configured to match your business needs.

This chapter guides you in planning a configuration that meets organization needs and the workload requirements of your host application.

 The plan and design workflow  Assessing business needs  Establishing data pool size  Requirements and recommendations for SnapShot Logical

Units

 Operating system considerations  Cascading SnapShot with TrueCopy  Cascading SnapShot with TrueCopy Extended Distance  Maximum supported capacity

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The plan and design workflow

The SnapShot planning effort consists of determining the number of V-VOLs required by your organization, the V -VOL(s)’ lifespan, that is, how long they must be held before being updated again, the frequency that snapshots are taken, and the size of the data pool. This information is found by analyzing business needs and measuring write workload sent by the host application to the primary volume.

The plan and design workflow consists of the following:

• Assess business needs.

• Determine how often a snapshot should be taken.

• Determine how long the snapshot should be held.

• Determine the number of snapshot copies required per P-VOL.

• Measure production system write workload.

• Size the data pool. (For a description of the data pool, see Data

pools on page 1-4.

These objectives are addressed in detail in this chapter. Two other tasks are required before your design can be implemented, which are also addressed in this chapter:

• When you have established your SnapShot system design, the system’s maximum allowed capacity must be calculated. This has to do with how the array manages storage segments.

• Equally important in the planning process are the ways that various operating systems interact with SnapShot.

Assessing business needs

Business needs have to do with how long back-up data needs to be retained and what the business or organization can tolerate when disaster strikes.

The following organizational priorities help determine the following:

• How often a snapshot should be made (frequency)

• How long a snapshot (the V-VOL) should be held (lifespan)

• The number of snapshots (V-VOLs) tha t will be required for the P-VOL.

Copy frequency

How often copies need to be made is determined by how much data could be lost in a disaster before business is significantly impacted.

To determine how often a snapshot should be taken

 Decide how much data could be lost in a disaster without

significant impact to the business.

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Ideally, a business desires no data loss. But in the real world, disasters occur and data is lost. You or your organization’s decision makers must decide the number of business transactions, the number of hours required to k e y in lost data, and so on.

If losing 4 hours of business transaction is acceptable, but not more, backups should be planned every 4 hours. If 24 hours of business transaction can be lost, backups may be planned every 24 hours.

Determining how often copies should be made is one of the factors used to determine data pool size. The more time that elapses between snapshots, the more data accumulates in the data pool. Copy frequency may need to be modified to reduce the data pool size.

Selecting a reasonable time between Snapshots

The length of time between snapshots, if too short or too long, can cause problems.

• When short periods are indicated by your company’s business needs, consider also that snapshots taken too frequently could make it impossible to recognize logical errors in the storage system. This would result in snapshots of bad data. How long does it take to notice and correct such logical errors? The time span for snapshots should provide ample time to locate and correct logical errors in the storage system.

• When longer periods between snapshots are indicated by business needs, consider that the longer the period, the more data accumulates in the data pool. Longer periods between backups require more space in the data pool.

This effect is multiplied if more than one V-VOL is used. If you hav e two snapshots of the P-VOL, then two V-VOLs are tracking changes to the P-VOL at the same time.

Establishing how long a copy is held (copy lifespan)

Copy lifespan is the length of time a copy (V-VOL) is held, before a new backup is made to the volume. Lifespan is determined by two factors:

• Your organization’ s data retention policy for holding onto backup copies.

• Secondary business uses of the backup data.

Lifespan based on backup requirements

• If the snapshot is to be used for tape backups, the minimum lifespan must be => the time required to copy the data to tape. For example:

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Hours to copy a V-VOL to tape = 3 hours V-VOL lifespan => 3 hours

• If the snapshot is to be used as a disk-based backup available for online recovery, you can determine the lifespan by multiplying the number of generations of backup you want to keep online by the snapshot frequency. For example:

Generations held = 4 Snapshot frequency = 4 hours 4 x 4 = 16 hours V-VOL lifespan = 16 hours

Lifespan based on business uses

• If you use snapshot data (the V-VOL) for testing an application, the testing requirements determine the amount of time a snapshot is held.

• If snapshot data is used for development purposes, development requirements may determine the time the snapshot is held.

• If snapshot data is used for business reports, the reporting requirements can determine the backup’s lifespan.

Establishing the number of V-VOLs

V-VOL frequency and lifespan determ ine the number of V- VOLs your system needs per P-VO L.

For example: Suppose your data must be backed up every 12 hours, and business-use of the data in the V-VOL requires holding it for 48 hours. In this case, your SnapShot system would require 4 V-VOLs, since there are four 12-hour intervals during the 48-hour period. This is illustrated in Figure 2-1.

•

Figure 2-1: V-VOL Frequency, Lifespan

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Establishing data pool size

The data pool holds data from the P-VOL that is being replaced. By holding this original data in the data pool, the mirror image of the PVOL at the time of the snapshot is maintained.

You determine the siz e of the data pool that your system requires by:

• Measuring the amount of write workload that passes from the host application to the P-VOL. Write workload is the megabytes per second that are written to the primary volume over a specific time.

• Calculating the amount of data that would accumulate during the lifespan of your V-VOL.

• Multiplying the amount of data that accumulates by the number of V-VOLs.

•

Figure 2-2: Write workload and data pool size

Measuring workload data, sizing the data pool

To set up SnapShot, you must measure the amount of data that changes in your production system. The amount of data written to the primary volume indicates how large the data pool must be.

Workload data is collected using performance monitoring software on your operating system—preferably during the busiest time of month, quarter , and year. The goal is to collect data that shows y our system’s actual workloads during high peaks and spikes, when more is changing and the demands on the system are greatest.

To collect workload data and size the data pool

1. Using your operating system’s performance monitoring software, collect the following:

- Disk-write bytes/second for every physical volume that will

be replicated.

- Collect this data at 10 minute intervals.

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- Collect this data over a 4-6 week period that includes high peaks and spikes, and when the demands on the system are greatest.

•

2. At the end of the period, convert the data to MB/second and import into a spreadsheet tool. Figure 2-3 shows collected raw data, in megabytes per second in 10 minute segments.

•

Figure 2-3: Raw Data Example in MB/sec

3. Using the copy frequency established earlier, calculate averages over the collection period. Most spreadsheet tools have an average function. For example:

If copy frequency is 1 hour, then calculate 60 minute rolling averages using the values in 6 10-minute intervals.

If copy frequency is 4 hours, then calculate 240 minute rolling averages using the values in 24 10-minute intervals.

Figure 2-4 illustrates 60-minute rolling averages.

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•

Figure 2-4: Rolling Averages Calculated Using V-VOL Frequency

Example rolling-average procedure using Microsoft Excel:

a. In cell C4, type =Average(b2:b7). b. Press Enter.

This instructs the tool to calculate the average value in cells

B2 through B7 and populates C4 with that data. c. Copy the value in C4. d. Highlight cells C5 to the last C cell in the last row of workload

data in the spreadsheet. e. Right-click the highlighted cells and select the paste option.

Excel maintains the logic and increments the formula values

initially entered in C4. It then calculates all the point in time

averages and populates the C cells.

Figure 2-5 illustrates rolling averages graphed over raw

measurement data averages.

Planning and design 2-7

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•

Figure 2-5: Rolling Averages Graphed Over Raw Averages

4. Locate the maximum rolling average (RA) value in the C column. Using this peak value and the following formula, calculate the cumulative peak data change over the lifespan of a copy (V- VOL):

(RA peak MB/sec) x (V-VOL lifespan seconds) = (Cumulative data over V-VOL lifespan)

For example, if the RA peak is 25 MB/sec, and the V-VOL lifespan is 3600 seconds (1 hour), then:

25MB/sec x 3600 seconds = 90,000 MB

Cumulative data over a V-VOL’s 1-hour lifespan is 90,000 MB.

5. Calculate the base data pool size for your primary/virtual volumes by multiplying the MB size of one V-VOL in Step 4 by the number of V-VOLs, which was established earlier. For example:

90,000 MB

x 4 V-VOLS = 360,000 MB

This is the base data pool size for a SnapShot system in which the copy frequency is 1 hour, the copy lifespan is 4 hours, and the number of copies (V-VOLs) is 4.

6. It is highly recommended that a safety factor of 20%, be calculated. Do so using the following formula:

(Base data pool size) x 1.2. For example:

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360,000 MB x 1.2 = 432,000 MB

7. It is also advisable to factor in annual increases in data transactions. Do this by multiplying the base pool size by the percentage of expected annual growth. For example:

432,000 MB x 1.2 (20 percent growth rate for per year) = 518,400 MB

This is the size of the data pool with growth factored for the first year.

8. Repeat this step for each year the solution will be in place. For example:

518, 400 MB x 1.2 (20 percent growth rate for second year)

= 622,080 MB

This is the size of the data pool with growth factored for the second year.

Rule-of-thumb calculation

When write-workload has not been measured, Hitachi suggests the change rates shown in Table 2-1.

•

Table 2-1: Workload Rates when No Measurement

Snapshot lifespan

1-4 hours 10% 4-8 hours 15% 8-12 hours 20% 12-24 hours 25%

Suggested write workload

change rate

To calculate data pool size using rule-of-thumb change rate

1. Use the following formula:

Data Pool size = (P-VOL x % of changed data x 2.5 safety rate) x number of V-VOLs

For example, if the P-VOL = 1 TB and one snapshot is taken per 24 hours, then:

1 TB x 25% change rate x 25% safety rate of = 625 GB

2. Multiply the data pool size by the number of V-VOLs. Thus: 4 V-VOLs x 625 GB = 2500 GB (2.5 TB).

Data pool key points

• The data pool must be on the same controller as the P-VOL and V-VOL(s).

• Data pool capacity should be at least 20 GB.

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• Up to 64 volumes can be assigned to a data pool.

• When a volume is assigned to a data pool, it is no longer recognized by a host.

Requirements and recommendations for SnapShot Logical Units

Please review the following key rules and recommendations regarding P-VOLS, V-VOLS, and data pools. See Appendix A,

Specifications, for general specifications required for SnapShot.

• Primary and secondary volumes must be set up prior to making SnapShot copies.

• The P-VOL and S-VOL must be assigned to the same controller.

• Assign four or more disks to SnapShot LUs for optimal host and copying performance.

• Volumes used for other purposes should not be assigned as a primary volume. If such a volume must be assigned, move as much of the existing write workload to non-SnapShot volumes as possible.

• If multiple P-VOLs are located in the same drive, the status of the pairs should stay the same (Simplex, Paired, and Split). When status differs, performance is difficult to estimate.

RAID configuration for LUs assigned to SnapShot

Please observe the following regarding RAID levels when setting up SnapShot pair volumes, data pools, command devices, and Differential Management LUs.

• More than one pair may exist on the same RAID group on the array. However, when more than two pair are assigned to the same group, the impact on performance increases. Therefore, it is recommended that when creating pairs within the same RAID group, you should standardize the controllers that control LUs in the RAID group.

• Performance is best when P-VOL and data pool are assigned to a RAID group consisting of SAS drives, SAS7.2K drives, SSD drives, or SAS (SED) drives. Performance decreases when located on SATA drives.

• Multiple data pool volumes can exist on a single array, but the RAID group for each data pool volume should be restricted only to that POOL, otherwise performance is impacted.

• Locate a P-VOL and associated data pool in different ECC groups within a RAID group, as shown in Figure 2-6. When they are in the same ECC group, performance decreases and the chance of failure increase.

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•

Figure 2-6: Locating P-VOL, Data Pool in Separate ECC Groups

• The P-VOL and data pool require a RAID level with redundancy. RAID 0 is not supported.

• The P-VOL and data pool may exist on different RAID lev els and/ or number of drives in RAID. Performance improves, however, when the RAID levels and number of drives are the same.

Table 2-2 shows RAID configurations for the P-VOL and data

pool.

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•

Table 2-2: P-VOL and Data Pool RAID Configuration

P-VOL Data Pool

RAID 1+0 (N = 1 to 8)

RAID 5 (N = 4) (see Note 1)

RAID 5 (When N = 4) (see Note 1)

RAID 5 (When N = 8) (see Note 1)

RAID 6 (When N = 4) (see Note 2)

RAID 6 (When N = 8) (see Note 2)

RAID 6 (When N = 4) (see Note 2)

Amount of

User Data

RAID 1+0 (N = 1 to 8)

RAID 5 (N = 4) (see Note 1)

RAID 1+0 (N = 1 to 8) 1 1.25+2 = 3.25 1/3.25

RAID 5 (When N = 4) (see Note 1)

RAID 5 (When N = 8) (see Note 1)

RAID 6 (When N = 4) (see Note 2)

RAID 6 (When N = 8) (see Note 2)

RAID 5 (When N = 4) (see Note 1)

14 ¼

1 2+1.25 = 3.25 1/3.25

1 1.25+1.25 = 2.5 1/2.5

1 1.125+1.125 =

1 1.5+1.5 = 3 1/3

1 1.25+1.25 = 2.5 1/2.5

1 1.5+1.25 = 2.75 1/2.75

Total Amount of

SnapShot

2.25

Share of User

Data

1/2.25

Note 1: Capacity = (1+1/N) where N = Number of data drives in RAID

Note 2: Capacity = (1+2/N) where N = Number of data drives in RAID

• RAID 5 (4D+1)/RAID 5 (4D+1) is the recommended configuration because 4D+1P is a recommended configuration for performance. It is also a balanced ratio of redundancy and user data related to RAID 5.

• When two or more command devices are located in the same AMS array, assign them to respective RAID groups. This safeguards the SnapShot system in the event of system malfunction, in which case both command devices would become unavailable.

• When two Differential Management LUs are located in the same AMS array, assign them to respective RAID groups. This safeguards the SnapShot system in the event of system malfunction, in which case both DM-LUs would become unavailable.

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Operating system considerations

The following sections provide recommendations and restrictions for SnapShot volumes.

Identifying P-VOL and V-VOL LUs on Windows

In the Navigator 2 GUI, the P-VOL and S- VOL are identi fied by their LU number. In Windows, LUs are identified by their HLUN. The following instructions provide procedures for the iSCSI and fibre channel interfaces.T o understand the mapping of a LUN on Windows, proceed as follows:

1. Identify the HLUN of your Windows disk. a. From the Windows Server 2003 Control Panel, select

Computer Management/Disk Administrator.

b. Right-click the disk whose HLUN you want to know, then

select Properties. The number displayed to the right of “LUN” in the dialog window is the HLUN.

2. Identify HLUN-to-LUN Mapping for the iSCSI interface as follows. (If using fibre channel, skip to Step 3.)

a. In the Navigator 2 GUI, select the desired array. b. In the array tree, click the Group icon, then click the iSCSI

Targets icon. c. Click the iSCSI Target that the volume is mapped to. d. On the screen for the host group, click the Logical Units tab.

The volumes mapped to the Host Group display. You can

confirm the LUN is mapped to the H-LUN.

WARNING! Your host group changes will be applied to multiple ports. This change will delete existing host group mappings and corresponding Host Group IDs, corrupting or removing data associated with the host groups. To keep specified host groups you do not want to remove, please cancel this operation and make changes to only one host group at a time.

3. Identify HLUN-to-LUN Mapping for the Fibre Channel interface, as follows:

a. In the Navigator 2 GUI, select the desired array. b. In the array tree that displays, click the Groups icon, then

click the Host Groups icon in the Groups tree.

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c. On the Host Groups screen, select a Host Group. d. On the host group screen, select the Logical Units tab. Find

the identified H-LUN. The LUN displays in the next column.

e. If the HLUN is not present on a host group target screen, on

the Host Groups screen, select another Host group and repeat Step d.

LU mapping

You cannot pair a P-VOL and V -VOL when their mapping information has not been defined in the configuration definition file. To prevent a host from recognizing a P-VOL or V- VOL, use LUN Manager to either map them to a port that is not connected to the host or map them to a host group that does not have a registered host. If y ou use Storage Navigator instead of LUN Manager, you need only perform this task with either the P-VOL or V-VOL.

Cluster and path switching software

Do not make the V-VOL an object of cluster or path switching software.

Microsoft Cluster Server (MSCS)

• A host cannot recognize both a P-VOL and its V-VOL at the same time. Map the P-VOL and V-VOL to separate hosts.

• When setting the V-VOL to be recognized by the host, use the CCI mount command rather than Disk Administrator.

• Do not place the MSCS Quorum Disk in CCI.

• The command device cannot be shared between different hosts in the cluster.

• Assign the exclusive command device to each host.

AIX

• A host cannot recognize both a P-VOL and its V-VOL at the same time. Map the P-VOL and V-VOL to separate hosts.

• Multiple V-VOLs per P-VOL cannot be recognized from the same host. Limit host recognition to one V-VOL.

Veritas Volume Manager (VxVM)

A host cannot recognize both a P-VOL and its V-VOL at the same time. Map the P-VOL and V-VOL to separate hosts.

Windows 2000

• A P-VOL and S-VOL cannot be made into a dynamic disk on Windows Server 2000.

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• Multiple V-VOLs per P-VOL cannot be recognized from the same host. Limit host recognition to one V-VOL.

• When mounting a volume, use the CCI mount command, even if using the Navigator 2 GUI or CLI to operate the pairs. Do not use the Windows mountvol command because the data residing in server memory is not flushed. The CCI mount command does flush data in server memory, which is necessary for SnapShot operations. For more information, see the Hitachi Adaptable

Modular Storage Command Control Interface (CCI) Reference Guide.

Windows Server and SnapShot configuration

• Multiple V-VOLs per P-VOL cannot be recognized from the same host. Limit host recognition to one V-VOL.

Volume mount:

• In order to make a consistent backup using a storage-based replication such as SnapShot, you must have a way to flush the data residing on the server memory to the array, so that the source volume of the replication has the complete data. Y ou can flush the date on the server memory using the umount command of CCI to un-mount the volume. When using the umount command of CCI for un-mount, use the mount command of CCI for mount. For more detail about mount/ umount command, see the Hitachi Adaptable Modular Storage Command Control Interface (CCI) Reference Guide.

• If you are using Windows Server 2003, mountvol /P to flush data on the server memory when un-mounting the volume is supported. Please understand the specification of the command and run sufficient test before you use it for your operation.

• In Windows Server 2008, use the umount command of CCI to flush the data on the memory of the server at the time of the unmount. Do not use the mountvol command of Windows standard. Refer to the Hitachi Adaptable Modular Storage Command Control Interface (CCI) Reference Guide for the detail of the restrictions of Windows Server 2008 when using the mount/umount command.

• Windows may write for the un-mounted volume. If a pair is resynchronized while remaining the data to the S-VOL on the memory of the server, the compatible backup cannot be collected. Therefore, execute the sync command of CCI immediately before re-synchronizing the pair for the unmounted S-VOL.

Volumes recognized by the host:

• If you recognize the P-VOL and S-VOL on Windows Server 2008 at the same time, it may cause an error because the P-VOL and S-VOL have the same disk signature. When the P-VOL and V-

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VOL have the same data, split the pair and then rewrite the disk signature so that they can retain different disk signatures can use the uniqueid command to rewrite a disk signature. See the

Hitachi Adaptable Modular Storage Command Control Interface (CCI) Reference Guide for the detail.

Command devices

When a path detachment, which is caused by a controller detachment or interface failure, continues for longer than one minute, the command device may be unable to be recognized at the time when recovery from the path detachment is made. To make the recovery, execute the "re-scanning of the disks" of Windows. When Windows cannot access the command device although CCI is able to recognize the command device, restart CCI.

Linux and LVM configuration

A host cannot recognize both a P-VOL and its V-VOL at the same time. Map the P-VOL and V-VOL to separate hosts.

Tru64 UNIX and SnapShot configuration

When rebooting the host, the pair should be split or un-recognized by the host. Otherwise, a system reboot takes a longer amount of time.

Concurrent use of Cache Partition Manager

When SnapShot is used together with Cache Partition Manager, please refer to the

Reference Guide

Hitachi Storage Navigator Modular 2 Storage Features

VMWare and SnapShot configuration

When creating a backup of the virtual disk in the vmfs format using SnapShot, shutdown the virtual machine that accesses the virtual disk, and then split the pair.

If one LU is shared by multiple virtual machines, shutdown all the virtual machines that share the LU when creating a backup. Therefore, it is not recommended to share one LU by multiple virtual machines in the configuration that creates a backup using SnapShot.

The VMWare ESX has a function to clone the virtual machine. Although the ESX clone function and SnapShot can be linked, cautions are required for the performance at the time of execution. For example, when the volume which becomes the ESX clone destination is a SnapShot P-VOL pair whose pair status is Paired, since the data is written to the S-VOL for writing to the P-VOL, the time required for a clone may become longer and the clone may be terminated abnormally in some cases. T o avoid this, we recommend

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the operation to make the SnapShot pair status Split or Simplex and to resynchronize or create the pair after executing the ESX clone. Also, it is the same for executing the functions such as migration the virtual machine, deploying from the template, and inflating the virtual disk and Space Reclamation.

Figure 2-7: VMWare ESX

When using the volume in the following status, disable (0) the VMFS3.HardwareAcceleratedLocking setting.

• The P-VOL or the S-VOL of the pairs which configures the cascade of ShadowImage and SnapShot.

When VMFS3.HardwareAcceleratedLocking is enabled (1) in the above-mentioned status, the volume may not be recognized. If the volume cannot be recognized, recover it by using this procedure:

1. Set VMFS3.HardwareAcceleratedLocking to disabled (0).

2. Rescan the storage.

When the virtual OS was created on the volume which could not be recognized, the virtual OS may not recover ev en after the volume is re-realized. In that case, do the following:

1. Delete the virtual OS once, and re-register the virtual OS in the data store of the volume which was re-realized.

2. At that time, when "Alarms" or "Authority" is set to the virtual OS, set it again after the re-registration.

3. Also, since the object ID of the virtual OS changes after the reregistration when the middleware is used, review the setting.

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Concurrent use of Dynamic Provisioning

Observe the following items:

• When the array firmware version is less than 0893/A, the DPVOLs created by Dynamic Provisioning cannot be set for a P-VOL of SnapShot. Moreover, when the array firmware version is less than 0893/A, the DP-VOLs cannot be added to the data pool used by SnapShot and TCE.

• Depending on the installed cache memory , Dynamic Provisioning and SnapShot may not be unlocked at the same time. To unlock Dynamic Provisioning and SnapShot at the same time, add cache memories. For the capacity of the supported cache memory, re fer to User data area of cache memory.

• The data pool used by SnapShot and TCE cannot be used as a DP pool of Dynamic Provisioning. Moreover, the DP pool used by Dynamic Provisioning cannot be used as data pools of SnapShot and TCE.

When the array firmware version is 0893/A or more, the DP-VOLs created by Dynamic Provisioning can be set for a P-VO L or a data pool of SnapShot. However, the normal LU and the DP-VOL cannot coexist in the same data pool.

The points remember when using SnapShot and Dynamic Provisioning together are described as follows. Refer to the Hitachi Adaptable Modular Storage Dynamic Provisioning User's Guide for the detailed information regarding Dynamic Provisioning. Hereinafter, the LU created in the RAID group is called a normal LU, and the LU created in the DP pool that is created by Dynamic Provisioning is called a DP-VOL.

• When using a DP-VOL as a DMLU, check that the free capacity (formatted) of the DP pool to which the DP-VOL belongs is 10 GB or more, and then set the DP-VOL as a DMLU. If the free capacity of the DP pool is less than 10 GB, the DP-VOL cannot be set as a DMLU.

• LU type that can be set for a P-VOL or a data pool of SnapShot The DP-VOL created by Dynamic Provisioning can be used for a

P-VOL or a data pool of SnapShot. Table 2-3 shows a combination of a DP-VOL and a normal LU that can be used for a P-VOL or a data pool of SnapShot.

Table 2-3: Combination of a DP-VOL and a Normal LU

TrueCopy

P-VOL

DP-VOL DP-VOL Available. When the pair status is Split, the data

TrueCopy

S-VOL

Contents

pool consumed capacity can be reduced compared to the normal LU.

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Table 2-3: Combination of a DP-VOL and a Normal LU

TrueCopy

P-VOL

DP-VOL Normal LU Available. The P-VOL consumed capacity can be

Normal LU DP-VOL Available. When the pair status is Split, the data

When creating the data pool using multiple DP-VOLs, the data pool

TrueCopy

S-VOL

Contents

reduced compared to the normal LU.

pool consumed capacity can be reduced compared to the normal LU.

cannot be created by combining the DP-VOLs which have different setting of Enabled/Disabled for Full Capacity Mode.

When both the P-VOL and the data pool use DP- VOLs, a pair cannot be created by combining the DP-VOLs which have different setting of Enabled/Disabled for Full Capacity Mode

• Assigning the controlled processor core of a P-VOL or a data pool

that uses the DP-VOL When the controlled processor core of the DP-VOL used for a P-

VOL or used for a data pool of SnapShot differs as well as the normal LU, switch the P-VOL controlled processor core assignment to the data pool controlled processor core automatically and create a pair. (In the case of AMS2500)

• DP pool designation of a P-VOL or a data pool that uses the DP-

VOL When using the DP-VOL created by Dynamic Provisioning for a P-

VOL or a data pool of SnapShot, using the DP-VOL designated in a separate DP pool of a P-VOL and a data pool is recommended.

• Setting the capacity when placing the DP-VOL in the data pool

When the pair status is Split, the old data is copied to the data pool while writing to the P-VOL. When using the DP-VOL created by Dynamic Provisioning as the data pool of SnapShot, the consumed capacity of the DP-VOL in the data pool is increased by storing the old data in the data pool. If the DP-VOL of more than or equal to the DP pool capacity is created and used for the data pool, this processing may deplete the DP pool capacity. When using the DP-VOL for the data pool of SnapShot, it is recommended to set the capacity making the over provisioning ratio 100% or less so that the DP pool capacity does not deplete.

Furthermore, the threshold value of the data pool of SnapShot and the threshold value of the DP pool differ . Even if the data pool use rate of SnapShot shows 10% or less, the DP pool consumed capacity may have exceeded Depletion Alert. Check whether the actual use rate falls below the respective threshold values of the data pool and DP pool of SnapShot.

• Pair status at the time of DP pool capacity depletion

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When the DP pool is depleted after operating the SnapShot pair that uses the DP-VOL created by Dynamic Provisioning, the pair status of the pair concerned may be a Failure. Table 2-4 shows the pair statuses before and after the DP pool capacity depletion. When the pair status becomes a Failure caused by the DP pool capacity depletion, add the DP pool capacity whose capacity is depleted, and execute the pair operation again.

Table 2-4: Pair Statuses before/after the DP Pool Capacity Depletion

Pair Statuses after the

Pair Statuses before the DP

Pool Capacity Depletion

DP Pool Capacity

Depletion belonging to

P-VOL

Simplex Simplex Simplex Reverse Synchronizing Reverse Synchronizing

Failure (See Note)

Paired Paired Paired

Split Split

Failure (See Note)

Failure Failure Failure

Pair Statuses after the DP

Pool Capacity Depletion

belonging to data pool

Reverse Synchronizing Failure (See Note)

Split Failure (See Note)

NOTE: When write is performed to the P-VOL or V-VOL to which the capacity depletion DP pool belongs, the copy cannot be continued and the pair status becomes a Failure.

• DP pool status and availability of pair operation When using the DP-VOL created by Dynamic Provisioning for a P-

VOL or a data pool of the SnapShot pair, the pair operation may not be executed depending on the status of the DP pool to which the DP-VOL belongs. Table 2-5 shows the DP pool status and availability of the SnapShot pair operation. When the pair operation fails due to the DP pool status, correct the DP pool status and execute the pair operation again.

Table 2-5: DP Pool Statuses and Availability of SnapShot Pair Operation

DP Pool Statuses, DP Pool Capacity Statuses, and DP Pool Optimization

Statuses

Pair Operation

Normal

Create pair00x0x0 Create pair

(split option)

00x0x0

Capacity in

Growth

Capacity

Depletion

Regressed Blocked

Optimization

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Table 2-5: DP Pool Statuses and Availability of SnapShot Pair Operation

DP Pool Statuses, DP Pool Capacity Statuses, and DP Pool Optimization

Statuses

Pair Operation

Normal

Split pair 0 0 x 0 x 0 Resync pair0 0x0x0 Restore pair0 0x0x0 Delete pair000000

Capacity in

Growth

Capacity

Depletion

Regressed Blocked

DP in

Optimization

NOTE: When the DP pool was created or the capacity was added, the formatting operates for the DP pool. If pair creation, pair resynchronization, or restoration is performed during the formatting, depletion of the usable capacity may occur. Since the formatting progress is displayed when checking the DP pool status, check if the sufficient usable capacity is secured according to the formatting progress, and then start the operation.

• Operation of the DP-VOL during SnapShot use When using the DP-VOL created by Dynamic Provisioning for a P-

VOL or a data pool of SnapShot, any of the operations among the capacity growing, capacity shrinking, LU deletion, and Full Capacity Mode changing of the DP-VOL in use cannot be executed. To execute the operation, delete SnapShot pair of which the DP-VOL to be operated is in use, and then execute it again.

• Operation of the DP pool during SnapShot use When using the DP-VOL created by Dynamic Provisioning for a P-

VOL or a data pool of SnapShot, the DP pool to which the DP-VOL in use belongs cannot be deleted. To execute the operation, delete the SnapShot pair of which the DP-VOL is in use belonging to the DP pool to be operated, and then execute it again. The attribute edit and capacity addition of the DP pool can be executed usually regardless of the SnapShot pair.

• Cascade connection A cascade can be performed on the same conditions as the

normal LU (refer to Cascade connection of SnapShot with

TrueCopy on page 1-12). However, the firmware version of the

array including the DP-VOL needs to be 0893/A or more.

User data area of cache memory

If SnapShot is used to secure a part of the cache memory, the user data area of the cache memory decreases. Also, by using TCE and Dynamic Provisioning together, the user data area may further decrease. Table 2-6 to Table 2-13 show the cache memory secured

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capacity and the user data area when using the program product. For Dynamic Provisioning, the user data area differs depending on DP Capacity Mode. Refer to the Hitachi Adaptable Modular Storage Dynamic Provisioning User's Guide for detailed information.

Table 2-6: Supported Capacity of the Regular Capacity Mode (H/

W Rev. is 0100)

(1 of 2)

Management

Array Type Cache Memory

Capacity for

Dynamic

Provisioning

AMS2100 1 GB/CTL 80 MB -

2 GB/CTL 512 MB 4 GB/CTL 2 GB

AMS2300 1 GB/CTL 140 mb -

2 GB/CTL 512 MB 4 GB/CTL 2 GB 8 GB/CTL 4 GB

AMS2500 2 GB/CTL 300 MB 512 MB

4 GB/CTL 1.5 GB 6 GB/CTL 3 GB 8 GB/CTL 4 GB 10 GB/CTL 5 GB 12 GB/CTL 6 GB 16 GB/CTL 8 GB

Capacity

Secured for

SnapShot or TCE

Table 2-7: Supported Capacity of the Regular Capacity Mode (H/

W Rev. is 0100)

Capacity

Secured for

Array Type

Dynamic

Provisioning

and TCE or

SnapShot

AMS2100 - 590 MB 59 0 MB N/A

580 1,520 MB 1,440 MB 940 MB 2,120 MB 3,520 MB 3,460 MB 1,400 MB

User Data

Area when

Dynamic

Provisioning,

TCE, and

SnapShot are

Disabled

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(2 of 2)

User Data

Area when

Provisioning

Using

Dynamic

User Data

Area when

Using

Dynamic

Provisioning

and TCE or

SnapShot

Page 75

Table 2-7: Supported Capacity of the Regular Capacity Mode (H/

W Rev. is 0100)

(2 of 2)

Capacity

Secured for

Array Type

Dynamic

Provisioning

and TCE or

SnapShot

AMS2300 - 500 MB 500 MB N/A

660 MB 1,440 MB 1,300 MB 780 MB 2,200 MB 3,280 MB 3,120 MB 1,080 MB 4,240 MB 7,160 MB 7,020 MB 2,920 MB

AMS2500 800 MB 1,150 MB 850 MB N/A

1,830 MB 2,960 MB 2,660 MB 1,130 MB 3,360 MB 4,840 MB 4,560 MB 1,480 MB 4,400 MB 6,740 MB 6,440 MB 2,340 MB 5,420 MB 8,620 MB 8,320 MB 3,200 MB 6,440 MB 10,500 MB 10,200 MB 4,060 MB 8,480 MB 14,420 MB 14,120 MB 5,940 MB

User Data

Area when

Dynamic

Provisioning,

TCE, and

SnapShot are

Disabled

User Data

Area when

Using

Dynamic

Provisioning

User Data

Area when

Provisioning

and TCE or

SnapShot

Using

Dynamic

Table 2-8: Supported Capacity of the Regular Capacity Mode (H/

W Rev. is 0200)

Array Type (the

H/W Rev. is

Cache Memory

0200)

AMS2100 1 GB/CTL 80 MB -

2 GB/CTL 512 MB 4 GB/CTL 2 GB

AMS2300 1 GB/CTL 140 MB -

2 GB/CTL 512 MB 4 GB/CTL 2 GB 8 GB/CTL 4 GB

(1 of 2)

Management

Capacity for

Dynamic

Provisioning

Capacity

Secured for

SnapShot or TCE

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Table 2-8: Supported Capacity of the Regular Capacity Mode (H/

W Rev. is 0200)

(1 of 2)

Array Type (the

H/W Rev. is

Cache Memory

0200)

AMS2500 2 GB/CTL 300 MB 512 MB

4 GB/CTL 1.5 GB 6 GB/CTL 3 GB 8 GB/CTL 4 GB 10 GB/CTL 5 GB 12 GB/CTL 6 GB 16 GB/CTL 8 GB

Management

Capacity for

Dynamic

Provisioning

Capacity

Secured for

SnapShot or TCE

Table 2-9: Supported Capacity of the Regular Capacity Mode (H/

Array Type

W Rev. is 0200)

Capacity

Secured for

Dynamic

Provisioning

and TCE or

SnapShot

User Data

Area when

Dynamic

Provisioning,

TCE, and

SnapShot are

Disabled

(2 of 2)

User Data

Area when

Provisioning

Using

Dynamic

User Data

Area when

Using

Dynamic

Provisioning

and TCE or

SnapShot

AMS2100 - 590 MB 59 0 MB N/A

580 1,390 MB 1,310 MB 810 MB 2,120 MB 3,360 MB 3,280 MB 1,220 MB

AMS2300 - 500 MB 50 0 MB N/A

660 MB 1,340 MB 1,200 MB 680 MB 2,200 MB 3,110 MB 2,970 MB 930 MB 4,240 MB 6,490 MB 6,800 MB 2,700 MB

AMS2500 800 MB 1,150 MB 850 MB N/A

1,830 MB 2,780 MB 2,480 MB 950 MB 3,360 MB 4,660 MB 4,360 MB 1,280 MB 4,400 MB 6,440 MB 6,140 MB 2,040 MB 5,420 MB 8,320 MB 8,020 MB 2,900 MB 6,440 MB 9,980 MB 9,680 MB 3,540 MB 8,480 MB 14,060 MB 13,760 MB 5,580 MB

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Table 2-10: Supported Capacity of the Maximum Capacity Mode

(H/W Rev. is 0100) (1 of 2)

Management

Array Type Cache Memory

Capacity for

Dynamic

Provisioning

AMS2100 1 GB/CTL 210 MB -

2 GB/CTL 512 MB 4 GB/CTL 2 GB

AMS2300 1 GB/CTL 310 MB -

2 GB/CTL 512 MB 4 GB/CTL 2 GB 8 GB/CTL 4 GB

AMS2500 2 GB/CTL 520 MB 512 MB

4 GB/CTL 1.5 GB 6 GB/CTL 3 GB 8 GB/CTL 4 GB 10 GB/CTL 5 GB 12 GB/CTL 6 GB 16 GB/CTL 8 GB

Capacity

Secured for

SnapShot or TCE

Table 2-11: Supported Capacity of the Maximum Capacity Mode

(H/W Rev. is 0100) (2 of 2)

Capacity

Secured for

Array

Type

Dynamic

Provisioning

and TCE or

SnapShot

AMS2100 - 590 MB N/A N/A

710 MB 1,520 MB 1,310 MB 810 MB 2,270 MB 3,520 MB 3,310 MB 1,250 MB

AMS2300 - 500 MB N/A N/A

830 MB 1,440 MB 1,130 MB 610 MB 2,350 MB 3,280 MB 2,970 MB 930 MB 4,410 MB 7,160 MB 6,850 MB 2,750 MB

User Data

Area when

Dynamic

Provisioning,

TCE, and

SnapShot are

Disabled

User Data

Area when

Using

Dynamic

Provisioning

User Data

Area when

Using

Dynamic

Provisioning

and TCE or

SnapShot

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Table 2-11: Supported Capacity of the Maximum Capacity Mode

(H/W Rev. is 0100) (2 of 2)

Capacity

Secured for

Array

Type

Dynamic

Provisioning

and TCE or

SnapShot

AMS2500 1,022 MB 1,150 MB N/A N/A

2,078 MB 2,960 MB N/A N/A 3,600 MB 4,840 MB 4,320 MB 1,240 MB 4,620 MB 6,740 MB 6,220 MB 2,120 MB 5,640 MB 8,620 MB 8,100 MB 2,980 MB 6,660 MB 10,500 MB 9,980 MB 3,840 MB 8,700 MB 14,420 MB 13,900 MB 5,720 MB

User Data

Area when

Dynamic

Provisioning,

TCE, and

SnapShot are

Disabled

User Data

Area when

Using

Dynamic

Provisioning

User Data

Area when

Using

Dynamic

Provisioning

and TCE or

SnapShot

Table 2-12: Supported Capacity of the Maximum Capacity Mode

(H/W Rev. is 0200) (1 of 2)

Management

Array Type Cache Memory

Capacity for

Dynamic

Provisioning

AMS2100 1 GB/CTL 210 MB -

2 GB/CTL 512 MB 4 GB/CTL 2 GB

AMS2300 1 GB/CTL 310 MB -

2 GB/CTL 512 MB 4 GB/CTL 2 GB 8 GB/CTL 4 GB

AMS2500 2 GB/CTL 520 MB 512 MB

4 GB/CTL 1.5 GB 6 GB/CTL 3 GB 8 GB/CTL 4 GB 10 GB/CTL 5 GB 12 GB/CTL 6 GB 16 GB/CTL 8 GB

Capacity

Secured for

SnapShot or TCE

2-26 Planning and design

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Page 79

Table 2-13: Supported Capacity of the Maximum Capacity Mode

(H/W Rev. is 0200) (2 of 2)

Capacity

Secured for

Array

Type

Dynamic

Provisioning

and TCE or

SnapShot

AMS2100 - 590 MB N/A N/A

710 MB 1,390 MB 1,180 MB 680 MB 2,270 MB 3,360 MB 3,150 MB 1,090 MB

AMS2300 - 500 MB N/A N/A

830 MB 1,340 MB 1,030 MB 510 MB 2,350 MB 3,110 MB 2,800 MB 760 MB 4,410 MB 6,940 MB 6,630 MB 2,530 MB

AMS2500 1,022 MB 1,090 MB N/A N/A

2,078 MB 2,780 MB N/A N/A 3,600 MB 4,660 MB 4,140 MB 1,060 MB 4,620 MB 6,440 MB 5,920 MB 1,820 MB 5,640 MB 8,320 MB 7,800 MB 2,680 MB 6,660 MB 9,980 MB 9,460 MB 3,320 MB 8,700 MB 14,060 MB 13,540 MB 5,360 MB

User Data

Area when

Dynamic

Provisioning,

TCE, and

SnapShot are

Disabled

User Data

Area when

Using

Dynamic

Provisioning

User Data

Area when

Provisioning

and TCE or

Using

Dynamic

SnapShot

Windows 2000/Windows Server and Dynamic Disk

In an environment of the Windows Server 2000/Windows Server , you cannot use SnapShot pair volumes as dynamic disk. The reason for this restriction is because in this case if you restart Windows or use the Rescan Disks command after creating or re-synchronizing a SnapShot pair, there are cases where the V-VOL is displayed as Foreign in Disk Management and become inaccessable.

Planning and design 2-27

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Limitations of Dirty Data Flush Number

This setting determines the number of times processing is executed for flushing the dirty data in the cache to the drive at the same time. This setting is effective when SnapShot is enabled. When all the LUs in the array are created in the RAID group of RAID 1 or RAID 1+0 (SAS drives or the SAS (SED) drives configured and in the DP pool), if this setting is enabled, the dirty data flush number is limited even though SnapShot is enabled. When the dirty data flush number is limited, the response time in I/O, which has a low load and high Read rate, shortens. Note that, when T rueCopy or TCE are unlocked at the same time, this setting is not effective.

See Setting the System Tuning Parameter or for CLI, see Setting the

System Tuning Parameter for the setting method about the Duty

Data Flush Number Limit.

Formatting the DMLU in the Event of a Drive Failure

When the DMLU is in a RAID group or DP pool with RAID5 or RAID6 and a drive failure occurs on the RAID group or DP pool with no redundancy, the data in the DMLU will be incomplete and unusable.

At that time, for the firmware version of 08C3/F and later, the DMLU will automatically become unformatted, so make sure to format the DMLU.

For less than 08C3/F, ev e n tho u gh the DMLU will not automatically become unformatted, make sure to format the DMLU.

It is possible to format a DMLU without having to release the DMLU.

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Cascading SnapShot with TrueCopy

Both the SnapShot P-VOL and V-VOL can be cascaded (shared) with the TrueCopy P-VOL or S-VOL, as shown in Figure 2-8.

•

Figure 2-8: Basic SnapShot Cascade Examples with TrueCopy

Read/write and pair operations are limited when a SnapShot pair is cascaded with T rueCopy . Please see the appendix on cascading in the

Hitachi Adaptable Modular Storage TrueCopy Remote Replication User Guide (MK-DF978052) for full information.

Planning and design 2-29

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Cascading SnapShot with TrueCopy Extended Distance

The SnapShot P-VOL can be cascaded (shared) with both the primary and secondary TrueCopy Extended Distance (TCE) volumes, as shown in Figure 2-9. A V-VOL cannot be cascaded.

•

Figure 2-9: Basic SnapShot Cascade Examples with TrueCopy

Extended

The TCE pair can be cascaded only with the SnapShot P-VOL, but the following restriction is placed on the cascade connection.

• The restoration of the SnapShot pair cascaded with the TCE PVOL can be done only when the status of the TCE pair is Simplex, Split, or Pool Full.

• When restoring the SnapShot pair cascaded with the TCE S- VOL, it is required to make the status of the TCE pair Simplex or Split. The restoration can be done in the Takeover status, but it cannot be done when the status is Busy in which the S-VOL is being restored using the data pool data.

• When the TCE S-VOL is in the Busy status in which it is being restored using the data pool data, the Read/Write instruction cannot be issued to the SnapShot V-VOL cascaded with the TCE S-VOL.

SnapShot requires restart to store the resource for the data pool management in the cache memory at the time of installation. This resource, however, is common to the resource for the data pool management of TCE. Therefore, when using SnapShot and TCE together, restart it only once when either one is installed first.

V-VOLs of up to 32 generations can be made even in the case where the P-VOL of SnapShot is cascaded with the P-VOL and S- VOL of TCE in the same way as in the case where no cascade connection is made.

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Read/write and pair operations are limited when a SnapShot pair is cascaded with TCE. Please see the appendix on cascading in the

Hitachi Adaptable Modular Storage TrueCopy Extended Distance User Guide (MK-DF978054) for full information.

Maximum supported capacity

The SnapShot function restricts P-VOL/data pool capacity.

• When SnapShot and ShadowImage are used on the same array

• When ShadowImage is used in addition to SnapShot The capacity you can assign to SnapShot replication volumes per

controller is limited, for the following reasons:

• The maximum capacity supported by a SnapShot pair depends on the ratio of P-VOL to data pool and cache memory.

• When using other copy systems and SnapShot together, the maximum supported capacity of the P-VOL may be restricted further.

In addition to this, capacity is managed by the AMS array in blocks of 15.75 KB for data volumes and 3.2 KB for data pools. For example, when a P-VOL block’s actual size is 16 KB, the array manages it as two blocks of 15.75 KB, or 31.5 KB. Data pool capacity is managed in the same way but at 3.2 KB per block.

•

NOTE: In a dual-controller array, the calculations must be performed for both controllers.

This section provides formulas for calculating your existing or planned SnapShot volume capacity and comparing it to the maximum supported capacity for your particular controller and its cache memory size.

SnapShot capacity must be calculated for both of the following:

1. The ratio of SnapShot and TCE (if used) capacity to data pool capacity. Capacity is calculated using the following volumes:

- SnapShot P-VOLs

- TCE P-VOLs and S-VOLs (if used)

- All data pools

2. Concurrent use of TCE and ShadowImage. If SnapShot is used concurrently also, it is included in this calculation. Capacity is calculated using the following volumes, if used:

- SnapShot P-VOLs

- TCE P-VOLs and S-VOLs

- TrueCopy P-VOLs and S-VOLs

- ShadowImage S-VOLs

Planning and design 2-31

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•

NOTE: A portion of cache memory is assigned to SnapShot for internal operations. For more information, please see Appendix D, Using SnapShot

with Cache Partition Manager.

SnapShot and TCE capacity

When TCE is used, SnapShot and TCE share common data pool resources. Therefore, you calculate their managed capacities together. If TCE is not used, you only calculate SnapShot’s capacity.

All formulas, tables, graphs and examples pertain to one controller. On dual controller arrays, you must perform calcu l ations for both controllers.

Managed capacity is calculated here, per controller, using the following formula:

Size all SnapShot P-VOLs + Size of all TCE P-VOLs (if used) + Size of all TCE S-VOLs (if used) + / 5 + size of all data pool volumes < Maximum Supported Capacity

Maximum supported capacity is shown in Table 2-14.

•

Table 2-14: Maximum Supported Capacities, Cache Size

per Controller

(SnapShot P-VOLs,

Cache Memory

per Controller

AMS2100 AMS2300 AMS2500

2 GB per CTL 1.4 TB Not supported Not supported 4 GB per CTL 6.2 TB 6.2 TB Not supported 8 GB per CTL Not supported 12.0 TB 12.0 TB 16 GB per CTL Not supported Not supported 24.0 TB

TCE P-VOLs, S-VOLs, Data Pools)

Example:

To calculate capacity when only SnapShot is used

In this example, the array and cache memory per controller is AMS 2300/4 GB.

1. List the size of each P-VOL in the Storage system. For example:

P-VOL 1 = 100 GB P-VOL 2 = 50 GB

2. Calculate managed P-VOL capacity, using the formula:

ROUNDUP (P-VOL capacity / 15.75) * 15.75

For example:

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P-VOL1: ROUNDUP (100 / 15.75) = 7

7 * 15.75 = 110.25 GB, the managed P-VOL Capacity

P-VOL2: ROUNDUP (50 / 15.75) = 4

4 * 15.75 = 63 GB, the managed P-VOL Capacity

3. List all data pools and their sizes. For example:

Data pool 1 = 100 GB Data pool 2 = 60 GB

4. Calculate managed data pool capacity, using the formula:

ROUNDUP (data pool capacity / 3.2) * 3.2

For example:

Data pool 1: ROUNDUP (100 / 3.2 = 32) 32 * 3.2 = 102.4 GB, the managed data pool capacity Data pool 2: ROUNDUP (60 / 3.2 = 19) 19 * 3.2 = 60.8 GB, managed data pool capacity

5. Calculate maximum capacity using the follow i ng e qu a tion:

(Total P-VOL capacity) / 5 + (Total Data Pool capacity) < = 800 GB

For example:

Total PVOL size = 173.25 GB Total data pool size = 163.2 GB

Thus:

173.25 GB / 5 = 34.65 GB

34.65 GB + 163.2 GB = 197.85 GB

In this example, the SnapShot maximum capacity is 197.85 GB, well below the maximum supported capacity shown in Table 2-

14.

To calculate capacity when SnapShot and TCE are used

1. Add the total managed capacities for SnapShot P-VOLs and TCE P-VOLs and S-VOLs. For example:

Total SnapShot P-VOL managed capacity = 173 GB Total TCE P-VOL, S-VOL managed capacity = 221 GB 173 GB + 221 GB = 394 GB

2. Divide the sum by 5. For example:

394 GB / 5 = 77 GB

3. Add the quotient to total data pool capacity. The following uses the example data pool capacity from above:

77 GB = 61 = 138 GB

Managed capacity is well below maximum supported capacity.

Planning and design 2-33

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Maximum Supported Capacity of P-VOL and Data Pool

Table 2-15 to Table 2-17 show the maximum supported capacities of

the P-VOL and the data pool for each cache memory capacity, and the formula for calculating the previous capacities.

Table 2-15: Formula for Calculating Maximum Supported

Capacity Value for P-VOL/Data Pool (AMS2100)

Capacity of Cache Memory

Installed

1 GB/CTL Not supported. 2 GB/CTL Total P- VOL of SnapShot and P-VOL (S- VOL)

4 GB/CTL Total P- VOL of SnapShot and P-VOL (S- VOL)

Capacity Spared for the Differential

Data (Shared by SnapShot and TCE)

of TCE capacity ÷ 5 + Total data pool capacity < 1.4 TB

of TCE capacity ÷ 5 + Total data pool capacity < 6.2 TB

Table 2-16: Formula for Calculating Maximum Supported

Capacity Value for P-VOL/Data Pool (AMS2300)

Capacity of Cache Memory

Installed

1 GB/CTL Not supported. 2 GB/CTL Total P- VOL of SnapShot and P-VOL (S- VOL)

4 GB/CTL Total P- VOL of SnapShot and P-VOL (S- VOL)

8 GB/CTL Total P- VOL of SnapShot and P-VOL (S- VOL)

Capacity Spared for the Differential

Data (Shared by SnapShot and TCE)

of TCE capacity ÷ 5 + Total data pool capacity < 1.4 TB

of TCE capacity ÷ 5 + Total data pool capacity < 6.2 TB

of TCE capacity ÷ 5 + Total data pool capacity < 12.0 TB

Table 2-17: Formula for Calculating Maximum Supported

Capacity Value for P-VOL/Data Pool (AMS2500)

Capacity of Cache Memory

Installed

2 GB/CTL T otal P- VOL of SnapShot and P-VOL (S- VOL)

4 GB/CTL T otal P- VOL of SnapShot and P-VOL (S- VOL)

6 GB/CTL T otal P- VOL of SnapShot and P-VOL (S- VOL)

2-34 Planning and design

Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

Capacity Spared for the Differential

Data (Shared by SnapShot and TCE)

of TCE capacity ÷ 5 + Total data pool capacity < 1.4 TB

of TCE capacity ÷ 5 + Total data pool capacity < 4.7 TB

of TCE capacity ÷ 5 + Total data pool capacity < 9.4 TB

Page 87

Table 2-17: Formula for Calculating Maximum Supported

Capacity Value for P-VOL/Data Pool (AMS2500)

Capacity of Cache Memory

Installed

8 GB/CTL T otal P- VOL of SnapShot and P-VOL (S- VOL)

10 GB/CTL T otal P- VOL of SnapShot and P-VOL (S- VOL)

12 GB/CTL T otal P- VOL of SnapShot and P-VOL (S- VOL)

16 GB/CTL T otal P- VOL of SnapShot and P-VOL (S- VOL)

No SnapShot-TCE cascade configuration

In no SnapShot-TCE cascade configuration, you need to add all volumes of SnapShot and TCE in Table 2-15 to Table 2-17.

1 TB×4 LU ÷ 5 + less than 0.6 TB < 1.4 TB

Capacity Spared for the Differential

Data (Shared by SnapShot and TCE)

of TCE capacity ÷ 5 + Total data pool capacity < 12.0 TB

of TCE capacity ÷ 5 + Total data pool capacity < 15.0 TB

of TCE capacity ÷ 5 + Total data pool capacity < 18.0 TB

of TCE capacity ÷ 5 + Total data pool capacity < 24.0 TB

Figure 2-10: No SnapShot-TCE cascade configuration

Planning and design 2-35

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SnapShot-TCE cascade configuration

In a SnapShot-TCE cascade configuration, you do not need to add volumes of TCE in Table 2-15 to Table 2-17. You need only to add volumes of SnapShot in the formula.

1 TB×2 LU ÷ 5 + less than 1 TB < 1.4 TB

Figure 2-11: SnapShot-TCE cascade configuration

2-36 Planning and design

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SnapShot, TCE, ShadowImage concurrent capacity

If ShadowImage is used on the same controller as SnapShot, managed capacity for concurrent use must also be calculated and compared to maximum supported capacity. If TCE or Tr ue Copy is used also, it is included in concurrent-use calculations.

Managed concurrent-use capacity is calculated using the following formula:

SnapShot: Maximum supported capacity value of P-VOL (TB) = Maximum SnapShot single capacity

- (Total ShadowImage S-VOL capacity / 17)

- (Total TrueCopy P-VOL and S-VOL capacity / 17)

- (Total TCE P-VOL and S-VOL capacity x 3

SnapShot maximum single capacity is shown in Table 2-18.

Table 2-19 on page 2-39 through Table 2-22 on page 2-40 show

how closely capacity between data volumes and data pool volumes must be managed. These tables are provided for your information. Also, Figure 2-12 on page 2-40 shows a graph of how the ratio of data volume to data pool volume relates to maximum supported capacity.

•

Table 2-18: SnapShot Maximum Single Capacity, per Controller

Equipment Type

AMS2100 1 GB per CTL Not supported

AMS2300 1 GB per CTL Not supported

AMS2500 2 GB per CTL 30

Mounted Memory

Capacity

2 GB per CTL 46 4 GB per CTL 56

2 GB per CTL 42 4 GB per CTL 116 8 GB per CTL 233

4 GB per CTL 116 6 GB per CTL 163 8 GB per CTL 210 10 GB per CTL 280 12 GB per CTL 350 16 GB per CTL 420

Single Maximum Supported

Capacity (TB)

Planning and design 2-37

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Example

In the following example, array and cache memory capacity are AMS2100 and 2 GB.

SnapShot: Maximum supported capacity value of P-VOL (TB) = Maximum SnapShot single capacity

- (Total ShadowImage S-VOL capacity / 17)

- (Total TrueCopy P-VOL and S-VOL capacity / 17)

- (Total TCE P-VOL and S-VOL capacity x 3

1. SnapShot Maximum single capacity = 46 TB

2. Divide the total ShadowImage S-VOL capacity by 17. For example:

Total SI S-VOL = 4 TB (4000 GB) 4000 GB / 17 = 235.3 GB

3. Subtract the quotient from the TCE maximum single capacity . F or example:

46 TB (46000 GB) - 235 GB = 45765 GB

4. Divide the total TrueCopy P-VOL and S-VOL capacity by 17. For example:

Total TrueCopy P-VOL and S-VOL capacity = 20 TB (20000 GB)

20000 GB / 17 = 1176 GB

5. Subtract this quotient from the remaining SnapShot maximum single capacity. For example:

45765 GB - 1176 GB = 44589 GB

6. Multiply total TCE P-VOL and S-VOL capacity by 3. For example:

Total TCE P-VOL and S-VOL capacity = 600 GB 600 GB x 3 = 1800 GB

7. Subtract this product from the remaining SnapShot maximum single capacity. For example:

44589 GB - 1800 GB = 42789 GB, the capacity left for SnapShot P-VOLs on the controller.

•

NOTE: When SnapShot is enabled, a portion of cache memory is assigned to it. Please review Appendix D, SnapShot with Cache Partition Manager for more information.

If your system’s maximum capacity exceeds the maximum allowed capacity, you can do one or more of the following:

• Change the P-VOL size

• Reduce the number of P-VOLs

• Change the data pool size

• Reduce the number of V-VOLs

• Reduce the lifespan of the V-VOL

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• Reduce ShadowImage P-VOL/S-VOL sizes

Cache limitations on Data and Data Pool volumes

This section provides comparisons in capacity between the data volumes and the data pool volumes under the limitations of the AMS controllers’ cache memory . The values in the tables and graph in this section are calculated from the formulas and maximum supported capacity in SnapShot and TCE capacity on page 2-32.

•

NOTE: “Data volumes” in this section consist of SnapShot P-VOLs, and TCE P-VOLs and S-VOLs (if used).

•

Table 2-19: P-VOL to Data Pool Capacity Ratio on AMS

2100 when Cache Memory is 2 GB per CTL

Ratio All P-VOL Capacity

to All Data Pool Capacity

1:0.5 2.0 : 1.0

1:1 1.1 : 1.1 1:3 0.4 : 1.2

•

All P-VOL Capacity

to All Data Pool Capacity (TB)

Table 2-20: P-VOL to Data Pool Capacity Ratio on

AMS 2100/2300 when Cache Memory is 4 GB per CTL

Ratio of All P-VOL Capacity

to All Data Pool Capacity

AMS 2100/2300 AMS 2100/2300

1:0.5 8.8 : 4.4

1:1 5.1 : 5.1 1:3 1.9 : 5.7

•

All P-VOL Capacity

to All Data Pool Capacity

(TB)

Table 2-21: P-VOL to Data Pool Capacity Ratio on

AMS 2300/2500 when Cache Memory is 8 GB per CTL

Ratio of All P-VOL Capacity

to All Data Pool Capacity

1:0.5 17.1 : 8.5

1:1 10.0 : 10.0 1:3 3.7 : 11.1

All P-VOL Capacity

to All Data Pool Capacity

Planning and design 2-39

Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

(TB)

Page 92

•

Table 2-22: P-VOL to Data Pool Capacity Ratio on

AMS 2500 when Cache Memory is 16 GB per CTL

Ratio of All P-VOL Capacity

to All Data Pool Capacity

1:0.5 34.2 : 17.1

1:1 20.0 : 20.0 1:3 7.5 : 22.5

•

All P-VOL Capacity

to All Data Pool Capacity

(TB)

Figure 2-12: Relation of Data Volume, Data Pool Volume

Capacities to Cache Size — per Controller

2-40 Planning and design

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Page 93

System requirements

This chapter describes minimum system requirements and supported platforms.

 System requirements  Supported platforms

System requirements 3–1

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Page 94

System requirements

The following table shows the minimum requirements for SnapShot. See Appendix A, Specifications for additional information.

Table 3-1: Storage System Requirements

Item Requirements

Firmware Version 0832/B or later is required for an AMS 2100 or 2300 array where the

hardware Rev. is 0100. Version 0840/A or later is required for an AMS 2500 arra y where the hardware

Rev. is 0100. Version 0890/A or later is required for an AMS 2100, 2300, and 2500 array

where the hardware Rev. is 0200.

Storage Navigator Modular 2

CCI Version 01-21-03/06 or later is required for the host when CCI is used for the

Number of controllers Two. The primary volume and data pool must be defined under the same

Command devices Maximum of 128. The command device is required only when CCI is used for

Differential Management LUs

Data pool Maximum of 64.

LU size V-VOL size must equal P-VOL size.

Version 3.21 or later is required for the management PC for an AMS 2100 or 2300 array where the hardware Rev. is 0100.

Version 4.00 or later is required for the management PC for an AMS 2500 arr ay where the hardware Rev. is 0100.

Version 9.00 or later is required for the management PC for an AMS2100, 2300, and 2500 where the hardware Rev. is 0200.

SnapShot operation.

controller.

SnapShot operation. The command device volume size must be greater than or equal to 33 MB.

Maximum of 2. DMLU size must be equal to or greater than 10 GB. Two DMLUs are recommended, each in a different RAID group.

- One per controller required; two per controller highly recommended.

- One or more pairs can be assigned to a data pool.

3-2 System requirements

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Displaying the hardware revision number

The hardware revision (Rev.) number can be displayed when an individual array is selected from the Arrays list using Navigator 2, version 9.00 or later.

•

System requirements 3-3

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Supported platforms

The following table shows the supported platforms and operating system versions required for SnapShot.

SUN Solaris 8 (SPARC)

PC Server (Microsoft) W indows 2000

HP HP-UX 11i V1.0 (PA-RISC)

IBM® AIX 5.1

Red Hat Red Hat Linux AS2.1 (IA32)

SGI IRIX 6.5.x

Table 3-2: Supported Platforms

Platforms Operating System Version

Solaris 9 (SPARC) Solaris 10 (SPARC) Solaris 10 (x86) Solaris 10 (x64)

Windows Server 2003 (IA32) Windows Server 2008 (IA32) Windows Server 2003 (x64) Windows Server 2008 (x64) Windows Server 2003 (IA64) Windows Server 2008 (IA64)

HP-UX 11i V2.0 (PA-RISC) HP-UX 11i V3.0 (PA-RISC) HP-UX 11i V2.0 (IPF) HP-UX 11i V3.0 (IPF) Tru64 UNIX 5.1

AIX 5.2 AIX 5.3

Red Hat Linux AS/ES 3.0 (IA32) Red Hat Linux AS/ES 4.0 (IA32) Red Hat Linux AS/ES 3.0 (AMD64/EM64T) Red Hat Linux AS/ES 4.0 (AMD64/EM64T) Red Hat Linux AS/ES 3.0 (IA64) Red Hat Linux AS/ES 4.0 (IA64)

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Installing and enabling

SnapShot

SnapShot must be installed on AMS using a license key. It can also be disabled or uninstalled. This chapter provides instructions for performing these tasks.

 Important prerequisite information  Installing or uninstalling SnapShot  Enabling or disabling SnapShot

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Important prerequisite information

If TrueCopy or TrueCopy Extended Distance (TCE) are installed, and you are installing/uninstalling or enabling/disabling SnapShot on the remote array, the operation causes the following to occur:

• The data paths for T rueCopy or T CE become blocked. The path is recovered from the blockade automatically after the array is restarted.

• TrueCopy or TCE pairs in Paired or Synchronizing status are changed to Failure pair status when the arr ay is restarted for the installation. If the array is not restarted, there is not effect on TCE pair status.

• Hitachi recommends changing TrueCopy or TCE pair status to Split before installing SnapShot on the remote array.

NOTE: When SnapShot is used together with TCE, restarting the array by the function that is installed after the function that was installed first is not required. The restart was done by the function that was installed first in order to ensure the resource for the data pool in the cache memory.

Installing or uninstalling SnapShot

A key code or key file is required to install or uninstall. If you do not have the key file or code, you can obtain it from the download page on the HDS Support Portal, http://support.hds.com

• Installation instructions are provided here for Navigator 2 GUI.

• For CLI instructions, see Appendix B, Operations using CLI (advanced users only).

Before installing or uninstalling SnapShot, verify that the Storage system is operating in a normal state. Installation/un-installation cannot be performed if a failure has occurred.

To install SnapShot without rebooting

1. In the Navigator 2 GUI, click the array in which you will install SnapShot.

2. Click Show & Configure Array.

3. Select the Install License icon in the Common Array Task.

The Install License screen appears.

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4. Select the Key File or Key Code radio button, and then enter the file name or key code. You may Browse for the key file.

5. A screen appears, requesting a confirmation to install SnapShot option. Click Confirm.

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6. A screen appears, completed to install the SnapShot option. Click Reconfigure Memory.

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7. A message appears, click Close.

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The Licenses list appears.

8. Confirm SNAPSHOT on the Name column of the Installed

Storage Features list, and Pending on the Reconfigure Memory Status column.

9. Check the check box of SNAPSHOT, and click Reconfigure Memory.

10.A message appears, click Confirm.

Installing and enabling SnapShot 4-3

Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide

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11.A message appears, click Close.

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The Licenses list appears.

12.Confirm the Reconfigure Memory Status is Reconfiguring(nn%) or Normal.

13.When the Reconfigure Memory Status is Reconfiguring(nn%), click Refresh Information after waiting for a while, and confirm the Reconfigure Memory Status changes to Normal.

14.When the Reconfigure Memory Status is Failed(Code- 01:Timeout), click Install License, and perform steps 4 to 12.

Code-01 occurs when the access from the host is frequent or the amount of the unwritten data in the cache memory is large.

15.When the Reconfigure Memory Status is Failed(Code-02: Failure of Reconfigure Memory), re-execute steps 7 to 12.

Code-02 occurs when the drive restoration processing starts in the background.

16.When the Reconfigure Memory Status is Failed(Code-04:

Failure of Reconfigure Memory), click the Resource of the Explorer menu, return to the Arrays screen.

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Code-04 occurs when the unwritten data in the cache memory cannot be saved to the drive.

17.Select the array in which you will install SnapShot, and click Reboot Array.

18.When the Reconfigure Memory Status is Failed(Code-03: Failure of Reconfigure Memory), ask the Support Center to solve the problem.

Code-03 occurs when the copy of the management information in the cache memory fails.

Installation of SnapShot is now complete.

4-4 Installing and enabling SnapShot

Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide