Hitachi AMS2100, AMS2300, AMS2500 User Manual

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

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.

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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

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

Contents iii

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

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

iv Contents

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

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

Contents v

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

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

vi Contents

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

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

viii Contents

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

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

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

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

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

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

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 ]

Preface xiii

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

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

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

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).

SnapShot overview 1–1

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

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.

1-2 SnapShot overview

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

•

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.

SnapShot overview 1-3

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

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.

1-4 SnapShot overview

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

•

Figure 1-2: V-VOL Maintains SnapShot Data

SnapShot overview 1-5

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

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.

1-6 SnapShot overview

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

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.

SnapShot overview 1-7

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

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

1-8 SnapShot overview

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

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.

SnapShot overview 1-9

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

• 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.

1-10 SnapShot overview

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

+ 180 hidden pages

Hitachi AMS2100, AMS2300, AMS2500 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Table of Contents

Preface

Intended audience

Product version

Release notes and readme

Product Abbreviations

Document revision level

Changes in this revision

Document organization

Document conventions

Convention for storage capacity values

Related documentation

Getting help

SnapShot overview

Copy-on-Write SnapShot software

Hardware and software configuration

How SnapShot works

Volume pairs — P-VOLs and V-VOLs

Data pools

Consistency group (CTG)

Differential Management LUs (DMLU)

LU Ownership of P-VOLs and data pools

Interfaces for performing SnapShot operations

Cascade connection of SnapShot with Simple DR

Cascade connection of SnapShot with Simple DR P-VOL