Hitachi AMS 2000 User Manual

Hitachi AMS 2000 Family TrueCopy Extended

Distance User Guide

F

AST

F

IND

L

INKS

Document organization

Release notes and readme

Getting help
Table of Contents

MK-97DF8054-23

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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

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• Russia – Import pending completion of notification formalities

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

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Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Table of Contents

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

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

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

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

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

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

Changes in this release . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii

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

Document conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xiv

Convention for storage capacity values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Related documents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

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

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

1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

How TCE works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Typical environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Volume pairs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

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

Guaranteed write order and the update cycle. . . . . . . . . . . . . . . . . . . . . . 1-4

Extended update cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

Consistency groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

Differential Management LUs (DMLU) . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

TCE interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

2 Plan and design — sizing data pools and bandwidth . . . . . . . . . 2-1

Plan and design workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Assessing business needs — RPO and the update cycle . . . . . . . . . . . . . . . . 2-2

Measuring write-workload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Collecting write-workload data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Calculating data pool size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

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Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Data pool key points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-7

Determining bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-8

3 Plan and design — remote path . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1

Remote path requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2

Management LAN requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3

Remote data path requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-3

WAN optimization controller (WOC) requirements . . . . . . . . . . . . . . . . . . .3-4

Remote path configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5

Fibre channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-5

Direct connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-6

Single FC switch, network connection . . . . . . . . . . . . . . . . . . . . . . . . . .3-7

Double FC switch, network connection . . . . . . . . . . . . . . . . . . . . . . . . .3-8

Fibre channel extender connection . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-9

Port transfer rate for Fibre channel. . . . . . . . . . . . . . . . . . . . . . . . . . .3-10

iSCSI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-11

Direct connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-11

Single LAN switch, WAN connection . . . . . . . . . . . . . . . . . . . . . . . . . .3-12

Multiple LAN switch, WAN connection. . . . . . . . . . . . . . . . . . . . . . . . .3-13

Single LAN switch, WOC, WAN connection. . . . . . . . . . . . . . . . . . . . . .3-14

Multiple LAN switch, WOC, WAN connection . . . . . . . . . . . . . . . . . . . .3-15

Multiple array, LAN switch, WOC connection with single WAN . . . . . . . .3-16

Multiple array, LAN switch, WOC connection with two WANs. . . . . . . . .3-17

Supported connections between various types of arrays . . . . . . . . . . . . . . .3-18

Notes when Connecting Hitachi AMS2000 Series to other arrays . . . . . . . .3-18

Using the remote path — best practices. . . . . . . . . . . . . . . . . . . . . . . . . . .3-20

4 Plan and design—arrays, volumes and operating systems. . . . .4-1

Planning workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2

Planning arrays—moving data from earlier AMS models. . . . . . . . . . . . . . . . .4-2

Planning logical units for TCE volumes. . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3

Volume pair and data pool recommendations . . . . . . . . . . . . . . . . . . . . . .4-3

Operating system recommendations and restrictions. . . . . . . . . . . . . . . . . . .4-4

Host time-out. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4

P-VOL, S-VOL recognition by same host on VxVM, AIX®, LVM . . . . . . . . . .4-4

HP server. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4

Windows Server 2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7

Windows Server 2003/2008. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7

Identifying P-VOL and S-VOL LUs on Windows. . . . . . . . . . . . . . . . . . . .4-8

Windows 2000 or Windows Server and TCE Configuration . . . . . . . . . . .4-9

Dynamic Disk in Windows 2000/Windows Server . . . . . . . . . . . . . . . . .4-10

VMWare and TCE Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-10

Concurrent Use of Dynamic Provisioning. . . . . . . . . . . . . . . . . . . . . . .4-11

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Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

User Data Area of Cache Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-16

Formatting the DMLU in the Event of a Drive Failure. . . . . . . . . . . . . . . . .4-22

Maximum supported capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-23

TCE and SnapShot capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-24

TCE, SnapShot, ShadowImage concurrent capacity . . . . . . . . . . . . . . . . .4-26

. . . . . . . . . . . . . . .Maximum Supported Capacity of P-VOL and Data Pool4-28

No SnapShot-TCE cascade configuration . . . . . . . . . . . . . . . . . . . . . . .4-29

SnapShot-TCE cascade configuration. . . . . . . . . . . . . . . . . . . . . . . . . .4-30

Cache limitations on data and data pool volumes . . . . . . . . . . . . . . . . . . .4-31

Cautions for Reconfiguring the Cache Memory. . . . . . . . . . . . . . . . . . . . .4-32

5 Requirements and specifications . . . . . . . . . . . . . . . . . . . . . . . . . .5-1

TCE system requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Displaying the hardware revision number . . . . . . . . . . . . . . . . . . . . . . . . 5-3

TCE system specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3

6 Installation and setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1

Installation procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2

Installing TCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

Enabling or disabling TCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6

Un-installing TCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8

Setup procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-11

Setting up DMLUs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-11

Setting up data pools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-12

Adding or changing the remote port CHAP secret. . . . . . . . . . . . . . . . . . .6-14

Setting up the remote path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-15

7 Pair operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-1

Operations work flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2

TCE operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

Checking pair status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

Creating the initial copy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3

Prerequisites and best practices for pair creation . . . . . . . . . . . . . . . . . . . 7-4

TCE setup wizard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

Create pair procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5

Splitting a pair. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6

Resynchronizing a pair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7

Swapping pairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-9

8 Example scenarios and procedures . . . . . . . . . . . . . . . . . . . . . . . .8-1

CLI scripting procedure for S-VOL backup. . . . . . . . . . . . . . . . . . . . . . . . . . 8-2

Scripted TCE, SnapShot procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4

Procedure for swapping I/O to S-VOL when maintaining local array . . . . . . . 8-9

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Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Procedure for moving data to a remote array. . . . . . . . . . . . . . . . . . . . . . .8-10

Example procedure for moving data . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-11

Process for disaster recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-11

Takeover processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-11

Swapping P-VOL and S-VOL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-12

Failback to the local array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-12

9 Monitoring and maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1

Monitoring pair status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-2

Monitoring data pool capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-5

Monitoring data pool usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-5

Expanding data pool capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-6

Changing data pool threshold value . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-6

Monitoring the remote path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-7

Changing remote path bandwidth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-7

Monitoring cycle time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-7

Changing cycle time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-8

Changing copy pace. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-8

Checking RPO — Monitoring P-VOL/S-VOL time difference. . . . . . . . . . . . . . .9-9

Routine maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-9

Deleting a volume pair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-9

Deleting data pools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-10

Deleting a DMLU. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-10

Deleting the remote path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-11

TCE tasks before a planned remote array shutdown. . . . . . . . . . . . . . . . .9-11

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-11

10 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-1

Troubleshooting overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-2

Correcting data pool shortage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-2

Correcting array problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-3

Delays in settling of S-VOL Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-4

Correcting resynchronization errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-4

Using the event log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-7

Recovering a TrueCopy path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-8

Miscellaneous troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10-10

A Operations using CLI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Installation and setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-2

Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-3

Enabling and disabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-5

Un-installing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-8

Setting the Differential Management Logical Unit. . . . . . . . . . . . . . . . . . .A-10

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Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Release a DMLU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-10

Setting the data pool. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-10

Setting the LU ownership. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-12

Setting the cycle time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-13

Setting mapping information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-13

Setting the remote port CHAP secret. . . . . . . . . . . . . . . . . . . . . . . . . . . A-14

Setting the remote path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-15

Deleting the remote path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-17

Pair operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Displaying status for all pairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Displaying detail for a specific pair . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-20

Creating a pair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-21

Splitting a pair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-21

Resynchronizing a pair. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

Swapping a pair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

Deleting a pair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-22

Changing pair information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-23

Monitoring pair status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-23

Confirming Consistency Group (CTG) status. . . . . . . . . . . . . . . . . . . . . . A-24

Procedures for failure recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25

Displaying the event log. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25

Reconstructing the remote path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-25

Sample script. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-26

B Operations using CCI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2

Setting the command device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-2

Setting LU mapping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-3

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

Setting the environment variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-6

Pair operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-7

Checking pair status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-7

Creating a pair (paircreate) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-8

Splitting a pair (pairsplit) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-8

Resynchronizing a pair (pairresync). . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-9

Suspending pairs (pairsplit -R) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-9

Releasing pairs (pairsplit -S). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-10

Splitting TCE S-VOL/SnapShot V-VOL pair (pairsplit -mscas) . . . . . . . . . . B-10

Confirming data transfer when status is PAIR . . . . . . . . . . . . . . . . . . . . B-13

Pair creation/resynchronization for each CTG. . . . . . . . . . . . . . . . . . . . . B-13

Response time of pairsplit command. . . . . . . . . . . . . . . . . . . . . . . . . . . B-15

Pair, group name differences in CCI and Navigator 2. . . . . . . . . . . . . . . . . B-18

C Cascading with SnapShot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

Contents vii

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Cascade configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-2

Replication operations supported . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-2

TCE operations supported . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-3

SnapShot operations supported . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-4

Status combinations, Read/write supported . . . . . . . . . . . . . . . . . . . . . . . . .C-4

Guidelines and restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-6

Cascading with SnapShot on the remote side . . . . . . . . . . . . . . . . . . . . . .C-6

TCE, SnapShot behaviors compared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-7

D Installing TCE when Cache Partition Manager is in use . . . . . . D-1

Initializing Cache Partition when TCE and SnapShot are installed . . . . . . . . . D-2

E Wavelength Division Multiplexing (WDM) and dark fibre. . . . . . .E-1

WDM and dark fibre. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .E-2

Glossary

Index

viii Contents

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Preface

This document provides instructions for planning, setting up, and
operating TrueCopy Extended Distance.

This preface includes the following information:

 Intended audience

 Product version

 Release notes and readme

 Changes in this release

 Changes in this release

 Document organization

 Document conventions

 Convention for storage capacity values

 Related documents

 Getting help

Preface ix

Hitachi AMS 2000 Family TrueCopy Extended Distance 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/B 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/or 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 TrueCopy Extended Distance User Guide

Changes in this release

•In Table 5-2 (page 5-3), added the parameter Remote Copy over iSCSI
in the WAN environment.

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, Overview Provides descriptions of TrueCopy Extended Distance

components and how they work together.

Chapter 2, Plan and
design — sizing data
pools and bandwidth

Chapter 3, Plan and
design — remote path

Chapter 4, Plan and
design—arrays,
volumes and operating
systems

Chapter 5,
Requirements and
specifications

Chapter 6, Installation
and setup

Chapter 7, Pair
operations

Chapter 8, Example
scenarios and
procedures

Chapter 9, Monitoring
and maintenance

Chapter 10,
Troubleshooting

Appendix A,
Operations using CLI

Appendix B,
Operations using CCI

Appendix C, Cascading
with SnapShot

Appendix D, Installing
TCE when Cache
Partition Manager is in
use

Provides instructions for measuring write-workload,
calculating data pool size and bandwidth.

Provides supported iSCSI and Fibre Channel
configurations, with information on WDM and dark fibre.

Discusses the arrays and volumes you can use for TCE.

Provides TCE system requirements and specifications.

Provides procedures for installing and setting up the TCE
system and creating the initial copy.

Provides information and procedures for TCE operations.

Provides backup, data moving, and disaster recovery
scenarios and procedures.

Provides monitoring and maintenance information.

Provides troubleshooting information.

Provides detailed Command Line Interface instructions for
configuring and using TCE.

Provides detailed Command Line Interface instructions for
configuring and using TCE.

Provides supported configurations, operations, etc. for
cascading TCE with SnapShot.

Provides required information when using Cache Partition
Manager.

Description

Preface xi

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Chapter/Appendix

Title

Description

Appendix E,
Wavelength

Provides a discussion of WDM and dark fibre for channel
extender.

Division
Multiplexing (WDM)
and dark fibre

Glossary Provides definitions for terms and acronyms found in this

document.

Index Provides links and locations to specific information in this

document.

xii Preface

Hitachi AMS 2000 Family TrueCopy Extended Distance 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

Angled brackets (< >) are also used to indicate variables.

screen/code Indicates text that is displayed on screen or entered by the user.

Example: # pairdisplay -g oradb

< > angled
brackets

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

the user or system. Example: # pairdisplay -g <group>

performing tasks more effectively.

text.

result in damage to the software or hardware.

Italic font is also used to indicate variables.

[ ] square
brackets

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

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

underline Indicates the default value. Example: [ a | b ]

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

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.

Preface xiii

Hitachi AMS 2000 Family TrueCopy Extended Distance 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

2

bytes

6

bytes

2

bytes

5

bytes

Related documents

The AMS 2000 Family user documentation is available on the Hitachi Data
Systems Portal: https://portal.hds.com. Please check this site for the most
current documentation, including important updates that may have been
made after the release of the product.

This documentation set consists of the following documents.

Release notes

• Adaptable Modular Storage System Release Notes

• Storage Navigator Modular 2 Release Notes

Please read the release notes before installing and/or using this product.
They may contain requirements and/or restrictions not fully described in
this document, along with updates and/or corrections to this document.

xiv Preface

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Installation and getting started

The following documents provide instructions for installing an AMS 2000
Family storage system. They include rack information, safety information,
site-preparation instructions, getting-started guides for experienced users,
and host connectivity information. The symbol
that contain initial configuration information about Hitachi AMS 2000 Family
storage systems.

 identifies documents

 AMS2100/2300 Getting Started Guide, MK-98DF8152

Provides quick-start instructions for getting an AMS 2100 or AMS 2300
storage system up and running as quickly as possible.

 AMS2500 Getting Started Guide,

MK-97DF8032 Provides quick-start instructions for getting an AMS 2500
storage system up and running as quickly as possible

AMS 2000 Family Site Preparation Guide, MK-98DF8149

Contains site planning and pre-installation information for AMS 2000
Family storage systems, expansion units, and high-density expansion
units. This document also covers safety precautions, rack information,
and product specifications.

AMS 2000 Family Fibre Channel Host Installation Guide,

MK-08DF8189

Describes how to prepare Hitachi AMS 2000 Family Fibre Channel
storage systems for use with host servers running supported operating
systems.

AMS 2000 Family iSCSI Host Installation Guide, MK-08DF8188

Describes how to prepare Hitachi AMS 2000 Family iSCSI storage
systems for use with host servers running supported operating systems.

Storage and replication features

The following documents describe how to use Storage Navigator Modular 2
(Navigator 2) to perform storage and replication activities.

Storage Navigator 2 Advanced Settings User’s Guide, MK-97DF8039

Contains advanced information about launching and using Navigator 2
in various operating systems, IP addresses and port numbers, server
certificates and private keys, boot and restore options, outputting
configuration information to a file, and collecting diagnostic information.

Preface xv

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Storage Navigator Modular 2 User’s Guide, MK-99DF8208

Describes how to use Navigator 2 to configure and manage storage on
an AMS 2000 Family storage system.

AMS 2000 Family Dynamic Provisioning Configuration Guide,

MK-09DF8201

Describes how to use virtual storage capabilities to simplify storage
additions and administration.

Storage Navigator 2 Storage Features Reference Guide for AMS,

MK-97DF8148

Contains concepts, preparation, and specifications for Account
Authentication, Audit Logging, Cache Partition Manager, Cache
Residency Manager, Data Retention Utility, LUN Manager, Performance
Monitor, SNMP Agent, and Modular Volume Migration.

AMS 2000 Family Copy-on-write SnapShot User Guide, MK-97DF8124

Describes how to create point-in-time copies of data volumes in AMS
2100, AMS 2300, and AMS 2500 storage systems, without impacting
host service and performance levels. Snapshot copies are fully read/
write compatible with other hosts and can be used for rapid data
restores, application testing and development, data mining and
warehousing, and nondisruptive backup and maintenance procedures.

AMS 2000 Family ShadowImage In-system Replication User Guide,

MK-97DF8129

Describes how to perform high-speed nondisruptive local mirroring to
create a copy of mission-critical data in AMS 2100, AMS 2300, and AMS
2500 storage systems. ShadowImage keeps data RAID-protected and
fully recoverable, without affecting service or performance levels.
Replicated data volumes can be split from host applications and used for
system backups, application testing, and data mining applications while
business continues to operate at full capacity.

AMS 2000 Family TrueCopy Remote Replication User Guide,

MK-97DF8052

Describes how to create and maintain multiple duplicate copies of user
data across multiple AMS 2000 Family storage systems to enhance your
disaster recovery strategy.

AMS 2000 Family TrueCopy Extended Distance User Guide,

MK-97DF8054 — this document

Describes how to perform bi-directional remote data protection that
copies data over any distance without interrupting applications, and
provides failover and recovery capabilities.

xvi Preface

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

AMS 2000 Data Retention Utility User’s Guide, MK-97DF8019

Describes how to lock disk volumes as read-only for a certain period of
time to ensure authorized-only access and facilitate immutable, tamper­proof record retention for storage-compliant environments. After data is
written, it can be retrieved and read only by authorized applications or
users, and cannot be changed or deleted during the specified retention
period.

Storage Navigator Modular 2 online help

Provides topic and context-sensitive help information accessed through
the Navigator 2 software.

Hardware maintenance and operation

The following documents describe how to operate, maintain, and administer
an AMS 2000 Family storage system. They also provide a wide range of
technical information and specifications for the AMS 2000 Family storage
systems. The symbol
configuration information about Hitachi AMS 2000 Family storage systems.

 identifies documents that contain initial

 AMS 2100/2300 Storage System Hardware Guide, MK-97DF8010

Provides detailed information about installing, configuring, and
maintaining an AMS 2100/2300 storage system.

 AMS 2500 Storage System Hardware Guide, MK-97DF8007

Provides detailed information about installing, configuring, and
maintaining an AMS 2500 storage system.

 AMS 2000 Family Storage System Reference Guide,

MK-97DF8008

Contains specifications and technical information about power cables,
system parameters, interfaces, logical blocks, RAID levels and
configurations, and regulatory information about AMS 2100, AMS 2300,
and AMS 2500 storage systems. This document also contains remote
adapter specifications and regulatory information.

AMS 2000 Family Storage System Service and Upgrade Guide,

MK-97DF8009

Provides information about servicing and upgrading AMS 2100, AMS
2300, and AMS 2500 storage systems.

AMS 2000 Family Power Savings User Guide, MK-97DF8045

Describes how to spin down volumes in selected RAID groups when they
are not being accessed by business applications to decrease energy
consumption and significantly reduce the cost of storing and delivering
information.

Preface xvii

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Command and Control (CCI)

The following documents describe how to install the Hitachi AMS 2000
Family Command Control Interface (CCI) and use it to perform TrueCopy
and ShadowImage operations.

AMS 2000 Family Command Control Interface (CCI) Installation
Guide, MK-97DF8122

Describes how to install CCI software on open-system hosts.

AMS 2000 Family Command Control Interface (CCI) Reference
Guide, MK-97DF8121

Contains reference, troubleshooting, and maintenance information
related to CCI operations on AMS 2100, AMS 2300, and AMS 2500
storage systems.

AMS 2000 Family Command Control Interface (CCI) User’s Guide,

MK-97DF8123

Describes how to use CCI to perform TrueCopy and ShadowImage
operations on AMS 2100, AMS 2300, and AMS 2500 storage systems.

Command Line Interface (CLI)

The following documents describe how to use Hitachi Storage Navigator
Modular 2 to perform management and replication activities from a
command line.

Storage Navigator Modular 2 Command Line Interface (CLI) Unified
Reference Guide, MK-97DF8089

Describes how to interact with all Navigator 2 bundled and optional
software modules by typing commands at a command line.

Storage Navigator 2 Command Line Interface Replication Reference
Guide for AMS, MK-97DF8153

Describes how to interact with Navigator 2 to perform replication
activities by typing commands at a command line.

xviii Preface

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Dynamic Replicator documentation

The following documents describe how to install, configure, and use Hitachi
Dynamic Replicator to provide AMS Family storage systems with continuous
data protection, remote replication, and application failover in a single,
easy-to-deploy and manage platform.

Hitachi Dynamic Replicator - Scout Release Notes, RN-99DF8211
Hitachi Dynamic Replicator - Scout Host Upgrade Guide,

MK-99DF8267

Hitachi Dynamic Replicator - Scout Host User Guide,

MK-99DF8266

Hitachi Dynamic Replicator - Scout Installation and Configuration
Guide, MK-98DF8213

Hitachi Dynamic Replicator - Scout Quick Install/Upgrade Guide,

MK-98DF8222

Getting help

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

Comments

• 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 days a week. If you need technical support, please log on to the
Hitachi Data Systems Portal for contact information: https://portal.hds.com

Ple as e se nd u s y o ur co m me nt s on th i s d oc u me nt : [e-mail].
Include the document title, number, and revision, and refer to specific
sections and paragraphs whenever possible.

Thank you! (All comments become the property of Hitachi Data Systems.)

Preface xix

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

xx Preface

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

1

Overview

This manual provides instructions for designing, planning,
implementing, using, monitoring, and troubleshooting TrueCopy
Extended Distance (TCE). This chapter consists of:

 How TCE works

 Typical environment

 TCE interfaces

Overview 1–1

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

How TCE works

With TrueCopy Extended Distance (TCE), you create a copy of your data at
a remote location. After the initial copy is created, only changed data
transfers to the remote location.

You create a TCE copy when you:

• Select a volume on the production array that you want to replicate

• Create a volume on the remote array that will contain the copy

• Establish a Fibre Channel or iSCSI link between the local and remote
arrays

• Make the initial copy across the link on the remote array.

During and after the initial copy, the primary volume on the local side
continues to be updated with data from the host application. When the host
writes data to the P-VOL, the local array immediately returns a response to
the host. This completes the I/O processing. The array performs the
subsequent processing independently from I/O processing.

Updates are periodically sent to the secondary volume on the remote side
at the end of the “update cycle”. This is a time period established by the
user. The cycle time is based on the recovery point objective (RPO), which
is the amount of data in time (2-hours’ worth, 4 hour’s worth) that can be
lost after a disaster, until the operation is irreparably damaged. If the RPO
is two hours, the business must be able to recover all data up to two hours
before the disaster occurred.

When a disaster occurs, storage operations are transferred to the remote
site and the secondary volume becomes the production volume. All the
original data is available in the S-VOL, from the last completed update. The
update cycle is determined by your RPO and by measuring write-workload
during the TCE planning and design process.

For a detailed discussion of the disaster recovery process using TCE, please
refer to Process for disaster recovery on page 8-11.

Typical environment

A typical configuration consists of the following elements. Many but not all
require user set up.

• Two AMS arrays—one on the local side connected to a host, and one on
the remote side connected to the local array. Connections are made via
Fibre Channel or iSCSI.

• A primary volume on the local array that is to be copied to the
secondary volume on the remote side.

• A differential management LU on local and remote arrays, which hold
TCE information when the array is powered down

1–2 Overview

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

• Interface and command software, used to perform TCE operations.
Command software uses a command device (volume) to communicate
with the arrays.

Figure 1-1 shows a typical TCE environment.

•

Volume pairs

When the initial TCE copy is completed, the production and backup volumes
are said to be “Paired”. The two paired volumes are referred to as the
primary volume (P-VOL) and secondary volume (S-VOL). Each TCE pair
consists of one P-VOL and one S-VOL. When the pair relationship is
established, data flows from the P-VOL to the S-VOL.

While in the Paired status, new data is written to the P-VOL and then
periodically transferred to the S-VOL, according to the user-defined update
cycle.

When a pair is “split”, the data flow between the volumes stops. At this time,
all the differential data that has accumulated in the local array since the last
update is copied to the S-VOL. This insures that its data is the same as the
P-VOL’s and is consistent and usable data.

During normal TCE operations, the P-VOL remains available for read/write
from the host. When the pair is split, the S-VOL also is available for read/
write operations from a host.

Figure 1-1: Typical TCE Environment

Overview 1–3

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Data pools

Data from the host is continually updated to the P-VOL, as it occurs. The
data pool on the local side stores the changed data that accumulates before
the next the update cycle. The local data pool is used to update the S-VOL.

Data that accumulates in the data pool is referred to as differential data
because it contains the difference data between the P-VOL and S-VOL.

The data in the S-VOL following an update is complete, consistent, and
usable data. When the next update is to begin, this consistent data is copied
to the remote data pool. This data pool is used to maintain previous point­in-time copies of the S-VOL, which are used in the event of failback.

Guaranteed write order and the update cycle

S-VOL data must have the same order in which the host updates the P-VOL.
When write order is guaranteed, the S-VOL has data consistency with the
P-VOL.

As explained in the previous section, data is copied from the P-VOL and local
data pool to the S-VOL following the update cycle. When the update is

complete, S-VOL data is identical to P-VOL data at the end of the cycle.

Since the P-VOL continues to be updated while and after the S-VOL is being
updated, S-VOL data and P-VOL data are not identical.

However, the S-VOL and P-VOL can be made identical when the pair is split.
During this operation, all differential data in the local data pool is
transferred to the S-VOL, as well as all cached data in host memory. This
cached data is flushed to the P-VOL, then transferred to the S-VOL as part
of the split operation, thus ensuring that the two are identical.

If a failure occurs during an update cycle, the data in the update is
inconsistent. Write order in the S-VOL is nevertheless guaranteed — at the
point-in-time of the previous update cycle, which is stored in the remote
data pool.

Figure 1-2 shows how S-VOL data is maintained at one update cycle back

of P-VOL data.

1–4 Overview

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

•

Extended update cycles

If inflow to the P-VOL increases, all of the update data may not be sent
within the cycle time. This causes the cycle to extend beyond the user­specified cycle time.

As a result, more update data in the P-VOL accumulates to be copied at the
next update. Also, the time difference between the P-VOL data and S-VOL
data increases, which degrades the recovery point value. In Figure 1-2, if a
failure occurs at the primary site immediately before time T3, for example,
data consistency in the S-VOL during takeover is P-VOL data at time T1.

When inflow decreases, updates again complete within the cycle time. Cycle
time should be determined according to a realistic assessment of write
workload, as discussed in Chapter 2, Plan and design — sizing data pools

and bandwidth.

Figure 1-2: Update Cycles and Differential Data

Overview 1–5

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Consistency groups

Application data often spans more than one volume. With TCE, 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 primary volumes as a consistency group allows TCE operations to
be performed on all volumes in the group concurrently. Write order in
secondary volumes is guaranteed across application logical volumes.

Figure 1-3 shows TCE operations with a consistency group.

•

Figure 1-3: TCE Operations with Consistency Groups

In this illustration, observe the following:

• The P-VOLs belong to the same consistency group. The host updates
the P-VOLs as required (1).

• The local array identifies the differential data in the P-VOLs when the
cycle is started (2) in an atomic manner. The differential data of the
group of the P-VOLs are determined at time T2.

• The local array transfers the differential data to the corresponding S­VOLs (3). When all differential data is transferred, each S-VOL is
identical to its P-VOL at time T2 (4).

• If pairs are split or deleted, the local array stops the cycle update for
the consistency group. Differential data between P-VOLs and S-VOLs is
determined at that time. All differential data is sent to the S-VOLs, and
the split or delete operations on the pairs completes. S-VOLs maintain

1–6 Overview

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

data consistency across pairs in the consistency group. The pair that is
using different data pool can be belongs to the same consistency group.

Differential Management LUs (DMLU)

The DMLU is an exclusive volume used for storing TrueCopy information
when the local or remote array is powered down. The DMLU is hidden from
a host. User setup is required on the local and remote arrays.

TCE interfaces

TCE can be setup, used and monitored using of the following interfaces:

• The GUI (Hitachi Storage Navigator Modular 2 Graphical User
Interface), which is a browser-based interface from which TCE 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 TCE can be setup and all basic pair operations can be
performed—create, split, resynchronize, restore, swap, and delete. The
GUI also provides these functionalities. CLI also has scripting capability.

• CCI (Hitachi Command Control Interface (CCI), which is 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 for performing failover and fall back
operations, and, on Windows 2000 Server, 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.

Overview 1–7

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

1–8 Overview

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

2

Plan and design — sizing

data pools and bandwidth

This chapter provides instructions for measuring write-workload
and sizing data pools and bandwidth.

 Plan and design workflow

 Assessing business needs — RPO and the update cycle

 Measuring write-workload

 Calculating data pool size

 Determining bandwidth

Plan and design — sizing data pools and bandwidth 2–1

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide

Plan and design workflow

You design your TCE system around the write-workload generated by your
host application. Data pools and bandwidth must be sized to accommodate
write-workload. This chapter helps you perform these tasks as follows:

• Assess business requirements regarding how much data your operation
must recover in the event of a disaster.

• Measure write-workload. This metric is used to ensure that data pool
size and bandwidth are sufficient to hold and pass all levels of I/O.

• Calculate data pool size. Instructions are included for matching data
pool capacity to the production environment.

• Calculate remote path bandwidth: This will make certain that you can
copy your data to the remote site within your update cycle.

Assessing business needs — RPO and the update cycle

In a TCE system, the S-VOL will contain nearly all of the data that is in the
P-VOL. The difference between them at any time will be the differential data
that accumulates during the TCE update cycle.

This differential data accumulates in the local data pool until the update
cycle starts, then it is transferred over the remote data path.

Update cycle time is a uniform interval of time during which differential data
copies to the S-VOL. You will define the update cycle time when creating the
TCE pair.

The update cycle time is based on:

• the amount of data written to your P-VOL

• the maximum amount of data loss your operation could survive during
a disaster.

The data loss that your operation can survive and remain viable determines
to what point in the past you must recover.

An ho ur ’s wo rth of da ta l os s me an s t hat yo ur re cov er y p oi nt i s o ne hou r a go .
If disaster occurs at 10:00 am, upon recovery your restart will resume
operations with data from 9:00 am.

Fifteen minutes worth of data loss means that your recovery point is 15
minutes prior to the disaster.

You must determine your recovery point objective (RPO). You can do this by
measuring your host application’s write-workload. This shows the amount
of data written to the P-VOL over time. You or your organization’s decision­makers can use this information to decide the number of business
transactions that can be lost, the number of hours required to key in lost
data and so on. The result is the RPO.

2–2 Plan and design — sizing data pools and bandwidth

Hitachi AMS 2000 Family TrueCopy Extended Distance User Guide