HP Remote Copy Software User Manual
3PAR Remote Copy® 2.3.1 User’s Guide
3PAR Inc.
4209 Technology Drive
Fremont, CA 94538 U.S.A.
Part No. 320-200175 Rev A
October 2009
Revision Notice
This is the first release of this manual. A complete revision history is provided at the end of this document.
Changes
The material in this document is for information only and is subject to change without notice. While reasonable efforts have been
made in the preparation of this document to assure its accuracy, 3PAR Inc. assumes no liability resulting from errors or omissions in
this document or from the use of the information contained herein.
3PAR reserves the right to make changes in the product design without reservation and without notification to its users.
Updates to the Documentation at 3PAR Central
Any updates to this document, or to other 3PAR technical documents, can be found by logging on to 3PAR Central’s Document
Control System from 3PAR’s Support page at http://support.3PAR.com.
3PAR Technical Support and Services
Contact your local service provider for technical support and services at http://www.3PAR.com/services.html.
Sales and Ordering Information
For sales and ordering information, contact:
3PAR Inc.
4209 Technology Drive
Fremont, CA 94538 U.S.A.
Telephone: 510–413–5999
Fax: 510–413–5699
E-mail: salesinfo@3PAR.com
Reader Comments and Suggestions
Please E-mail your comments and suggestions about this document to readercomments@3PAR.com.
Copyrights
© 2009 3PAR Inc. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any
form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written consent of 3PAR Inc.,
4209 Technology Drive, Fremont, CA 94538. By way of exception to the foregoing, the user may print one copy of electronic material
for personal use only.
Trademarks
3PAR, InServ, InForm, InSpire and Serving Information are registered trademarks of 3PAR Inc.
Microsoft, Windows, and Windows NT are either registered trademarks or trademarks of Microsoft Corporation.
UNIX is a registered trademark of The Open Group.
All other trademarks and registered trademarks are owned by their respective owners.
Federal Communications Commission Radio Frequency Interference Statement
WARNING: Changes or modifications to this unit not expressly approved by the party responsible for compliance could void the user’s
authority to operate the equipment.
This device complies with Part 15 of FFC Rules. Operation is subjected to the following two conditions (1) this device may not cause
harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired
operation.
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC rules.
These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a
commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in
accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a
residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own
expense.
InForm OS Version 2.3.1 Remote Copy User’s Guide
Table of Contents
1 Introduction
1.1 Audience 1.2
1.2 Related Documentation 1.2
1.3 Organization 1.3
1.4 Typographical Conventions 1.4
1.5 Advisories 1.5
2 Remote Copy Overview
2.1 Overview 2.3
2.2 Remote Copy Terms and Concepts 2.3
2.2.1 Remote Copy Terms 2.3
2.2.2 Remote Copy Concepts 2.4
2.3 Remote Copy Volume Groups 2.6
2.4 Remote Copy Pairs 2.6
2.5 Remote Copy Configuration 2.7
2.5.1 Bidirectional Configurations 2.7
2.5.2 Unidirectional Configurations 2.8
2.5.3 N-to-1 Configurations 2.9
2.5.4 1-to-N Configurations 2.11
2.5.5 Synchronous Long Distance Configuration 2.12
Table of Contents
iii
Remote Copy User’s Guide InForm OS Version 2.3.1
2.6 Remote Copy Targets 2.15
2.6.1 Target Definitions 2.15
2.7 Remote Copy Links 2.17
2.7.1 Sending Links 2.17
2.7.2 Receiving Links 2.18
2.8 Remote Copy Connections 2.18
2.8.1 IP Networks 2.19
2.8.2 Fibre Channel Networks 2.20
2.8.3 Fibre Channel over IP Networks 2.20
2.9 Remote Copy Operation 2.20
2.9.1 Volume Group Modes 2.22
2.9.1.1 Synchronous Mode 2.23
2.9.1.2 Asynchronous Periodic Mode 2.24
2.9.2 Synchronization Types 2.25
2.9.2.1 Asynchronous Periodic Mode Volume Groups 2.25
2.9.2.2 Synchronous Mode Volume Groups 2.28
2.9.3 Resynchronization Period 2.28
2.9.4 Manual Resynchronization 2.29
2.9.5 Concurrent Synchronization Limits 2.29
2.9.6 Throughput Limiting Option 2.30
2.9.7 Role Reversal 2.30
2.10 Remote Copy and 3PAR Virtual Domains 2.30
2.11 Use of Virtual Copy Snapshots 2.31
2.11.1 In Synchronous Mode 2.31
2.11.2 In Asynchronous Periodic Mode 2.32
2.12 Remote Copy and Thin Provisioning 2.33
2.12.1 Snapshots and Common Provisioning Groups 2.33
2.12.2 Thinly Provisioned Virtual Volumes 2.34
2.12.3 Fully Provisioned Virtual Volumes 2.35
2.13 Error Handling 2.35
2.13.1 Single Link Failure 2.35
iv
Table of Contents
InForm OS Version 2.3.1 Remote Copy User’s Guide
2.13.2 Double Link Failure 2.36
2.13.2.1 Synchronous Volume Groups 2.36
2.13.2.2 Asynchronous Periodic Groups 2.37
2.13.3 Remote Copy Failure Timeouts 2.37
2.13.4 Storage Server Failures 2.38
2.13.4.1 Failure of a Target 2.38
2.13.4.2 Failure of a Secondary Target 2.38
2.13.5 Write Errors 2.38
2.13.6 Read Errors 2.39
2.14 Requirements and Restrictions 2.41
2.14.1 N-to-1 Restrictions 2.43
2.14.2 1-to-N Restrictions 2.44
2.14.3 Synchronous Long Distance Restrictions 2.45
3 Remote Copy Setup
3.1 Available Setup Methods 3.2
3.2 Preparing for Setup 3.2
3.3 Gathering Necessary Information 3.3
3.4 Setting the Remote Copy Transport Layer 3.8
3.4.1 Setting Up Remote Copy Over IP 3.8
3.4.2 Setting Up the Remote Copy Interface for RCIP 3.9
3.4.2.1 Setting the Gateway 3.9
3.4.2.2 Verifying Connectivity 3.10
3.4.2.3 Increasing MTU (Optional) 3.11
3.4.3 Setting Up Remote Copy Over Fibre Channel 3.13
3.4.3.1 Setting Up the Remote Copy Interface for RCFC 3.14
3.4.4 Setting Up RCFC Over an IP Network 3.15
3.5 Setting Up Remote Copy 3.16
3.5.1 Setting Up Unidirectional Remote Copy 3.17
3.5.1.1 Setting Up the Primary Server 3.18
3.5.1.2 Setting Up the Backup Server 3.19
Table of Contents
v
Remote Copy User’s Guide InForm OS Version 2.3.1
3.5.1.3 Creating Remote Copy Volume Groups 3.21
3.5.1.4 Start Copying 3.23
3.5.1.5 Setting Up Additional Remote Copy Pairs 3.25
3.5.2 Setting Up Bidirectional Remote Copy 3.25
3.6 Synchronous Long Distance Remote Copy Setup 3.28
3.6.1 Setting Up the Primary Server 3.31
3.6.2 Setting Up the Backup Servers 3.32
3.6.3 Verifying Synchronous Long Distance Remote Copy Setup 3.34
3.6.4 Creating Synchronous Long Distance Remote Copy Volume Groups 3.36
3.7 Initial Synchronization Using Tape Backup 3.38
3.7.1 Synchronizing Volume Groups 3.38
4 Using Remote Copy
4.1 Management 4.2
4.2 Reversing Target Designations 4.2
4.3 Changing Remote Copy Mode for a Volume Group 4.3
4.4 Setting Remote Copy Volume Group Policies 4.4
4.5 Manual Resynchronization 4.5
4.6 Viewing Synchronization Details 4.5
4.7 Converting Standard Virtual Volumes 4.8
4.8 Modifying Virtual Volumes 4.9
4.8.1 Growing a Virtual Volume 4.9
4.8.2 Renaming a Virtual Volume 4.9
4.9 Limiting Throughput 4.10
4.10 Stopping Remote Copy 4.11
4.11 Remote Copy Commands 4.11
5 Performance and Scripting Considerations
5.1 Performance Notes for RCIP Configuration 5.1
5.1.1 Gigabit Ethernet Links 5.1
5.1.2 Initial Synchronization 5.2
vi
Table of Contents
InForm OS Version 2.3.1 Remote Copy User’s Guide
5.1.3 Distance 5.2
5.1.4 MTU Size 5.2
5.1.5 Autonegotiation 5.3
5.1.6 Remote Copy Mode 5.3
5.1.6.1 Asynchronous Periodic 5.3
5.1.6.2 Synchronous Mode 5.4
5.2 Performance Notes for RCFC Configuration 5.5
5.2.1 RCFC Links 5.5
5.2.2 Initial Sync 5.5
5.2.3 Distance 5.5
5.2.4 Remote Copy Mode 5.5
5.3 Scripting Notes 5.5
AQuick Setup Guide
A.1 Setting Up the Remote Copy Transport Layer for RCIP A.2
A.2 Setting Up the Remote Copy Transport Layer for RCFC A.3
A.3 Setting Up Remote Copy A.3
A.4 Setting Up Synchronous Long Distance Remote Copy A.7
B Remote Copy Commands
admitrcopylink B.3
admitrcopytarget B.5
admitrcopyvv B.7
controlport B.9
creatercopygroup B.18
creatercopytarget B.20
dismissrcopylink B.23
dismissrcopytarget B.25
dismissrcopyvv B.27
growvv B.29
Table of Contents
vii
Remote Copy User’s Guide InForm OS Version 2.3.1
removercopygroup B.31
removercopytarget B.33
setrcopygroup B.35
setrcopytarget B.43
setvv B.47
showport B.52
showrcopy B.57
showrctransport B.62
startrcopy B.66
startrcopygroup B.67
statport B.69
statrcopy B.74
stoprcopy B.77
stoprcopygroup B.79
syncrcopy B.81
C Example Setup and Disaster Recovery
C.1 Remote Copy Setup Examples C.2
C.2 Bidirectional Synchronous Disaster Recovery Example C.4
C.3 N-to-1 Asynchronous Periodic Disaster Recovery Example C.15
C.4 1-to-N Unidirectional Asynchronous Periodic Disaster Recovery Example C.27
C.5 Synchronous Long Distance Remote Copy Disaster Recovery Example C.38
C.5.1 Synchronous Backup Server Assumes Role of Primary Server C.43
C.5.2 Asynchronous Backup Server Assumes Role of Primary Server C.59
C.5.3 Asynchronous Backup Server Assumes Role of Primary Server -
No Data Transfer from the Synchronous Backup Server
C.6 Synchronous Long Distance Remote Copy for Data Migration C.96
C.80
viii
Table of Contents
InForm OS Version 2.3.1 Remote Copy User’s Guide
D Comparing MTU Speeds
Index
RH Revision History
Table of Contents
ix
Remote Copy User’s Guide InForm OS Version 2.3.1
Table of Contents
x
InForm OS Version 2.3.1 Remote Copy User’s Guide
1
Introduction
In this chapter
1.1 Audience 1.2
1.2 Related Documentation 1.2
1.3 Organization 1.3
1.4 Typographical Conventions 1.4
1.5 Advisories 1.5
This guide provides the information you need to configure and use 3PAR Remote Copy. It also
discusses special usage scenarios and how to handle problems.
3PAR Remote Copy is a product that allows you to copy virtual volumes from one InServ
storage server to another. The copy can be used for disaster recovery, for backup, or for data
migration.
3PAR Remote Copy requires that you use the InForm® CLI. Refer to the InForm OS Command
Line Interface Reference for complete instructions on using the InForm CLI. See Appendix B,
Remote Copy Commands for information on the use of specific CLI commands relevant for
Remote Copy.
Introduction
1.1
Remote Copy User’s Guide InForm OS Version 2.3.1
1.1 Audience
This guide is for System and Storage Administrators who monitor and direct system
configurations and resource allocation for 3PAR InServ® Storage Systems.
1.2 Related Documentation
The following documents also provide information related to InServ® Storage Servers and the
InForm® Operating System:
For Information About… Read the…
InServ Storage Server concepts and
terminology
CLI commands and their usage 3PAR InForm OS Command Line Interface
Using the InForm Management Console
(IMC) to configure and administer InServ
Storage Servers
Using the InForm Command Line Interface
(CLI) to configure and administer InServ
Storage Servers
Storage server hardware configurations,
component numbering and layout, and
system cabling
Identifying storage server components and
detailed alert information
3PAR InForm OS Concepts Guide
Reference
3PAR InForm OS Management Console
Online Help
3PAR InForm OS CLI Administrator’s
Manual
3PAR InServ E-Class/F-Class Storage Server
and Third-Party Rack Physical Planning
Manual
3PAR InServ S-Class/T-Class Storage Server
Physical Planning Manual
3PAR InForm OS Messages and Operator’s
Guide
1.2
Audience
InForm OS Version 2.3.1 Remote Copy User’s Guide
1.3 Organization
This guide is organized as follows:
■ Chapter 1, Introduction, (this chapter), provides an overview of this guide, including
information on audience, related documentation, and typographical conventions.
■ Chapter 2, Remote Copy Overview, gives an overview of 3PAR Remote Copy, that discusses
important terminology and concepts from a theoretical perspective.
■ Chapter 3, Remote Copy Setup, walks you through the process of setting up and
configuring Remote Copy on InServ Storage Servers. This chapter also describes how to
perform the initial synchronization using tape backup instead of the Remote Copy links.
■ Chapter 4, Using Remote Copy, provides instructions on using 3PAR Remote Copy, including
how to set Remote Copy group and target policies, how to limit throughput, and how to
stop Remote Copy operations.
■ Chapter 5, Performance and Scripting Considerations, gives best practice recommendations
for the use of 3PAR Remote Copy. The performance impact of Remote Copy is also discussed
in this chapter.
■ Appendix A, Quick Setup Guide, provides a summary for expert users on how to prepare
storage servers to use 3PAR Remote Copy to set up the Remote Copy connections between
the storage server pair(s) and to then start using 3PAR Remote Copy.
■ Appendix B, Remote Copy Commands, provides detailed information about the InForm CLI
commands used with Remote Copy. The format is the same as that of the InForm OS
Command Line Interface Reference.
■ Appendix C, Example Setup and Disaster Recovery, walks you through several example
setup and disaster recovery scenarios.
■ Appendix D, Comparing MTU Speeds, shows you how to configure a test volume group and
measure the initial volume synchronization throughput to measure the difference between
the 1500 and 9000 byte MTU settings.
This guide also contains a revision history and an index for your reference.
Organization
1.3
Remote Copy User’s Guide InForm OS Version 2.3.1
1.4 Typographical Conventions
This guide employs the following typographical conventions:
Typeface Meaning Example
ABCDabcd Used for dialog elements such as
titles, button labels, and other
screen elements.
ABCDabcd Used for paths, file names, and
screen output.
ABCDabcd Used to differentiate user input
from screen output.
<ABCDabcd>
<ABCDabcd> Used for variables in user input. #./java -jar inform.jar
Used for variables in file names,
paths, and screen output.
When prompted, click Finish to
complete the installation.
Open the file
\gui\windows\setup.exe
# cd /opt/3par/gui
Modify the content string by adding the
-P<x> option after
-P<x>
-jar inform.jar
1.4
Typographical Conventions
InForm OS Version 2.3.1 Remote Copy User’s Guide
1.5 Advisories
To avoid injury to people or damage to data and equipment, be sure to observe the cautions
and warnings in this guide. Always be careful when handling any electrical equipment.
NOTE: Notes are reminders, tips, or suggestions that supplement the procedures
included in this guide.
CAUTION: Cautions alert you to actions that can cause damage to equipment,
software, or data.
WARNING: Warnings alert you to actions that can cause injury to people or
irreversible damage to data or the operating system.
Advisories
1.5
Remote Copy User’s Guide InForm OS Version 2.3.1
1.6
Advisories
InForm OS Version 2.3.1 Remote Copy User’s Guide
2
Remote Copy Overview
In this chapter
2.1 Overview 2.3
2.2 Remote Copy Terms and Concepts 2.3
2.3 Remote Copy Volume Groups 2.6
2.4 Remote Copy Pairs 2.6
2.5 Remote Copy Configuration 2.7
2.5.1 Bidirectional Configurations 2.7
2.5.2 Unidirectional Configurations 2.8
2.5.3 N-to-1 Configurations 2.9
2.5.4 1-to-N Configurations 2.11
2.5.5 Synchronous Long Distance Configuration 2.12
2.6 Remote Copy Targets 2.15
2.7 Remote Copy Links 2.17
2.8 Remote Copy Connections 2.18
2.9 Remote Copy Operation 2.20
2.9.1 Volume Group Modes 2.22
Remote Copy Overview
2.1
Remote Copy User’s Guide InForm OS Version 2.3.1
2.9.2 Synchronization Types 2.25
2.9.3 Resynchronization Period 2.28
2.9.4 Manual Resynchronization 2.29
2.9.5 Concurrent Synchronization Limits 2.29
2.9.6 Throughput Limiting Option 2.30
2.9.7 Role Reversal 2.30
2.10 Remote Copy and 3PAR Virtual Domains 2.30
2.11 Use of Virtual Copy Snapshots 2.31
2.11.1 In Synchronous Mode 2.31
2.11.2 In Asynchronous Periodic Mode 2.32
2.12 Remote Copy and Thin Provisioning 2.33
2.12.1 Snapshots and Common Provisioning Groups 2.33
2.12.2 Thinly Provisioned Virtual Volumes 2.34
2.2
2.12.3 Fully Provisioned Virtual Volumes 2.35
2.13 Error Handling 2.35
2.13.1 Single Link Failure 2.35
2.13.2 Double Link Failure 2.36
2.13.3 Remote Copy Failure Timeouts 2.37
2.13.4 Storage Server Failures 2.38
2.13.5 Write Errors 2.38
2.13.6 Read Errors 2.39
2.14 Requirements and Restrictions 2.41
InForm OS Version 2.3.1 Remote Copy User’s Guide
2.1 Overview
3PAR Remote Copy is a product that allows you to copy virtual volumes from one
InServ Storage Server to another. The copy can be used for disaster recovery, for backup, or for
data migration.
3PAR Remote Copy requires that you use the InForm CLI. Refer to the InForm OS Command
Line Interface Reference and the InForm OS CLI Administrator’s Manual for complete
instructions on using the InForm CLI. See Appendix B, Remote Copy Commands for additional
instructions on the use of specific Remote Copy commands.
NOTE: All examples in this chapter show how to use 3PAR Remote Copy with the
default policies enabled. The default policies allow you to run most configuration
commands only on the primary storage system. See Setting Remote Copy Volume
Group Policies on page 4.4 and Remote Copy Commands on page 4.11 for
additional information.
NOTE: 3PAR Remote Copy requires 3PAR Remote Copy licenses for all storage
servers participating in a Remote Copy replication. Refer to the 3PAR InForm OS
Concepts Guide for additional information on licensing and features.
2.2 Remote Copy Terms and Concepts
This section provides an overview of the common Remote Copy terms and concepts used
throughout this manual.
2.2.1 Remote Copy Terms
Before using Remote Copy, review the following terms:
■ Remote Copy pair – the pair of storage servers on which Remote Copy operations are
performed. See Remote Copy Pairs on page 2.6 for additional information.
■ Remote Copy volume group – a group of virtual volumes that are logically related and
for which there is a cross-volume ordering of writes. Primary volume groups reside on the
Overview
2.3
Remote Copy User’s Guide InForm OS Version 2.3.1
local or primary server and secondary volume groups reside on the remote or backup
server. See Remote Copy Volume Groups on page 2.6 for additional information.
NOTE: Cross-volume ordering of writes refers to the preservation of related
writes. For example:
a A volume group contains volumes V1 and V2.
b The host application writes VV1 to V1 and then writes VV2 to V2.
c When mirrored with Remote Copy, VV1 is written to first, then VV2.
■ primary volume group – the set of volumes on the storage server to be copied.
■ secondary volume group – the set of copied volumes on the storage server.
■ local or primary server – the storage server on which the primary volume groups
originate.
■ remote or backup server – the storage server on which the copied volume groups reside.
■ target definition (target) – the description of a Remote Copy system on one server in the
Remote Copy pair. Each server in a Remote Copy pair must have a target definition for the
other server. Refer to Remote Copy Targets on page 2.15 for additional information.
■ Remote Copy links – the method by which information is sent and received between
Remote Copy targets. See Remote Copy Links on page 2.17 for detailed information.
2.2.2 Remote Copy Concepts
As stated earlier, 3PAR Remote Copy is a product that allows you to copy virtual volumes from
one InServ Storage Server to another. Generally, Remote Copy operations require at least two
storage servers (discussed in N-to-1 Configurations on page 2.9). For overview purposes, this
section focuses on a single pair of storage servers, or Remote Copy pair.
When setting up Remote Copy on the Remote Copy pair, the pair is set up in bidirectional
Remote Copy mode. In a bidirectional Remote Copy setup, both servers in the Remote Copy
pair serve as primary and backup servers in relation to one other. This relationship is illustrated
in Figure 2-1 that follows.
2.4
Remote Copy Terms and Concepts
InForm OS Version 2.3.1 Remote Copy User’s Guide
Primary
Volume
Group X
Secondary
Volume
Group Y.r
Secondary
Volume
Group X.r
Primary
Volume
Group Y
Group X to Group X.r
Group Y to Group Y.r
InServ1
InServ2
Natural direction
of data replication
Figure 2-1. Relationship of Primary Versus Secondary Volume Groups on Primary and Backup Storage
Servers
In Figure 2-1, InServ1 and InServ2 act as both primary and backup servers. The following
relationships are established:
■ Volume Group X (the primary volume group on storage server InServ1) is copied to
storage server InServ2 and exists there as the secondary volume group Volume Group
X.r. InServ2 acts as a backup server to InServ1 (the primary server).
■ Volume Group Y (the primary volume group on storage server InServ2) is copied to
storage server InServ1 and exists there as the secondary volume group Volume Group Y.r.
InServ1 acts as a backup server to InServ2 (the primary server).
■ In Remote Copy, the storage server on which you initially created a volume group is
identified as the local or primary server. The natural direction of data replication (the copy)
originates from that server. In the previous figure, Remote Copy was set up on InServ1.
Therefore the natural direction of the copy is from InServ1 to InServ2 for Volume
Group X.
Remote Copy Terms and Concepts
2.5
Remote Copy User’s Guide InForm OS Version 2.3.1
2.3 Remote Copy Volume Groups
Remote Copy operations are performed on groups of virtual volumes called Remote Copy
volume groups. A Remote Copy volume group is a group of volumes on the same storage
system that are logically related and for which there is a cross-volume ordering of writes.
Volume groups are used when data needs to be consistent across a group of volumes in order
for database or other applications to process data correctly.
Remote Copy uses volume groups to define a set of volumes for which applications might issue
dependent writes.
Remote Copy ensures that the data in the volumes within a group maintain write consistency.
When Remote Copy operations are started or stopped, this is done for the whole group. When
point-in-time snapshots of such volumes are created, writes to all volumes in the group are
blocked to assure a consistent point-in-time copy of the whole volume group.
2.4 Remote Copy Pairs
Remote Copy configurations are based on the relationship between a storage server pair, also
known as the Remote Copy pair. Within this pair, the primary storage server is the server that
holds the volumes that are copied to a backup server, also known as a remote storage server.
2.6
As described in N-to-1 Restrictions on page 2.43, a maximum of four primary storage servers
can use the same backup storage server. In such configurations, the backup storage server
participates in multiple pairs, one for each primary storage server. See Figure 2-4 for an
example of a configuration that uses multiple Remote Copy pairs.
NOTE: For any configuration, the backup storage server might be at the same
location as the primary storage server or servers, or it might reside at a remote
location. Disaster recovery applications often require that the backup storage
server reside at a remote location relative to the primary storage servers.
Remote Copy Volume Groups
InForm OS Version 2.3.1 Remote Copy User’s Guide
Primary
Volume
Secondary
Volume
InServ1
InServ2
Group X
Group X.r
Secondary
Volume
Group Y.r
Primary
Vol ume
Group Y
Direction of data
replication
Group X to Group X.r
Group Y to Group Y.r
2.5 Remote Copy Configuration
As stated previously, Remote Copy configurations are based on the relationship between a pair
of InServ Storage Servers (Remote Copy pair). The storage servers in the Remote Copy pair play
multiple roles at the same time. Both storage servers can function as both the primary and
backup servers and can hold primary and secondary volume groups. This configuration is
referred to as a bidirectional Remote Copy configuration. Conversely, a Remote Copy setup
where all groups are primary on one server and all groups are secondary on the other server is
referred to as unidirectional. A combination of bidirectional (for one Remote Copy pair) and
unidirectional configurations can be used in multi-Remote Copy pair setups (N-to-1 or
1-to-N configurations). Each configuration is discussed further in the sections that follow.
2.5.1 Bidirectional Configurations
In a bidirectional Remote Copy pair, each storage server provides backup for the other, but
only for selected volume groups. Figure 2-2 illustrates how this configuration might work with
a single Remote Copy pair.
Figure 2-2. Bidirectional Remote Copy
Remote Copy Configuration
2.7
Remote Copy User’s Guide InForm OS Version 2.3.1
Primary
Backup
Primary
Vol ume
Secondary
Volume
Storage Server
Storage Server
Group X
Group X.r
Direction of data
replication
Primary to Secondary Group
(InServ1)
(InServ2)
2.5.2 Unidirectional Configurations
In a unidirectional Remote Copy configuration, each storage server in the pair plays either the
role of the primary server or the backup server. In this configuration, the primary storage
server or servers holds all primary volume groups and the backup storage server holds all
secondary volume groups.
2.8
Remote Copy Configuration
Figure 2-3. Unidirectional Remote Copy
InForm OS Version 2.3.1 Remote Copy User’s Guide
2.5.3 N-to-1 Configurations
In N-to-1 Remote Copy configurations, a maximum of four primary storage servers use the
same secondary (backup) storage server. N-to-1 Remote Copy configurations can operate in
either a combination of bidirectional (for one Remote Copy pair) and unidirectional
functionality (as shown in Figure 2-4), or in complete unidirectional functionality. In the
following figure, unidirectional Remote Copy is maintained between Remote Copy pairs
InServ1 and InServ4, and Remote Copy pairs InServ2 and InServ4. Bidirectional Remote
Copy is maintained between Remote Copy pair InServ3 and InServ4.
NOTE: In an N-to-1 Remote Copy configuration, only one link can be
bidirectional. The secondary storage server must have four or more controller
nodes.
Remote Copy Configuration
2.9
Remote Copy User’s Guide InForm OS Version 2.3.1
Direction of data
replication
InServ1
InServ2
InServ3
InServ4
Primary
Volume
Group W
Primary
Volume
Group X
Secondary
Volume
Group W.r
Secondary
Volume
Group X.r
Primary
Volume
Group Y
Secondary
Volume
Group Y.r
Primary
Volume
Group Z
Secondary
Volume
Group Z.r
Group W to
Group W.r
Group X to
Group X.r
Group Y to
Group Y.r
Group Z to
Group Z.r
2.10
Remote Copy Configuration
Figure 2-4. N-to-1 Remote Copy
InForm OS Version 2.3.1 Remote Copy User’s Guide
Direction of data
replication
InServ2
InServ3
InServ1
Secondary
Vol ume
Group W.r
Secondary
Vol ume
Group X.r
Primary
Vol ume
Group W
Primary
Vol ume
Group X
Secondary
Vol ume
Group Z.r
Primary
Vol ume
Group Z
Group W to
Group W.r
Group X to
Group X.r
Group Z to
Group Z.r
2.5.4 1-to-N Configurations
In a 1-to-N Remote Copy configuration, a single primary storage server can use multiple
InServ Storage Servers as backup servers. For the current release, a 1-to-N Remote Copy
configuration has a maximum of two secondary (backup) targets. Like N-to-1 Remote Copy
configurations, 1-to N Remote Copy configurations can operate in either a combination of
bidirectional (for one Remote Copy pair) and unidirectional functionality (as shown in
Figure 2-5), or in complete unidirectional functionality. In the following figure, unidirectional
Remote Copy is maintained between Remote Copy pairs InServ1and InServ3. Bidirectional
Remote Copy is maintained between Remote Copy pair InServ1 and InServ2.
Figure 2-5. 1-to-N Remote Copy
Remote Copy Configuration
2.11
Remote Copy User’s Guide InForm OS Version 2.3.1
2.5.5 Synchronous Long Distance Configuration
In Synchronous Long Distance Remote Copy configurations, a single volume group is copied
directly to volumes on two other servers by admitting the volumes to groups with two targets.
Synchronous mode Remote Copy is used between the primary server and backup server that
are physically closer to each other where a high bandwidth/low latency connection is shared,
and asynchronous periodic mode Remote Copy is used between the primary server and backup
server that are physically farther apart sharing a lesser connection (see Synchronization Types
on page 2.25 for details about synchronous and asynchronous periodic modes). The
synchronous connection must be a Fibre Channel connection while the asynchronous periodic
connections can be either all Fibre Channel (over an IP network) or all IP.
In a Synchronous Long Distance Remote Copy configuration, if one backup server fails, Remote
Copy can still continue between the primary server and the second backup server. As shown in
Figure 2-6, when the backup server InServ2 fails, Remote Copy in asynchronous periodic mode
still continues between the primary server InServ1 and second backup server InServ3.
Conversely, if InServ3 failed, Remote Copy in synchronous mode would still continue between
InServ1 and InServ2.
NOTE: Synchronous Long Distance Remote Copy links cannot be bidirectional.
2.12
Remote Copy Configuration
InForm OS Version 2.3.1 Remote Copy User’s Guide
InServ1
(primary server)
InServ2
(backup server)
InServ3
(backup server)
Synchronous
Mode
Prior to InServ2 Failure
1
2
InServ2 Failure
InServ2
(backup server)
InServ3
(backup server)
Primary
Volum e
Group A
Secondary
Volum e
Group A
1
Secondary
Volum e
Group A
2
Secondary
Volum e
Group A
1
Secondary
Volum e
Group A
2
InServ1
(primary server)
Primary
Volum e
Group A
Asynchronous
ModePeriodic
Asynchronous
ModePeriodic
(standby link)
Figure 2-6. Synchronous Long Distance Remote Copy - One Backup Server Failure
Upon restoration of InServ2, data is transferred from InServ1 to InServ2 and synchronous
mode Remote Copy is restored between InServ1 and InServ2.
In the event of an primary server failure, one of the backup servers (typically the backup server
sharing a synchronous Remote Copy connection with the primary server) assumes the role of
the primary server and the second backup server then serves as the backup of the new primary
system. The volume on the new primary server is updated periodically on the backup server. As
shown in Figure 2-7, when the primary server InServ1 goes down, InServ2 becomes the
primary server and InServ3 becomes the backup server to InServ2.
Remote Copy Configuration
2.13
Remote Copy User’s Guide InForm OS Version 2.3.1
InServ1
(primary server)
InServ2
(backup server)
InServ3
(backup server)
Synchronous
Mode
Prior to InServ1 Failure
1
2
InServ1 Failure
InServ1
(failed)
InServ2
(primary server)
InServ3
(backup server)
Primary
Volum e
Group A
Secondary
Volum e
Group A
1
Secondary
Volum e
Group A
2
Primary
Volum e
Group A
Secondary
Volum e
Group A
Asynchronous
ModePeriodic
Asynchronous
ModePeriodic
(standby link)
NOTE: Either backup server can be set up to assume the role of the primary server
in the event of failover. See Chapter 3, Remote Copy Setup for information.
2.14
Figure 2-7. Synchronous Long Distance Remote Copy - Primary Server Failure
Upon restoration of InServ1:
■ Data is transferred from InServ2 to InServ1, and InServ1 is restored to the primary server.
■ InServ2 and InServ3 are restored as backup servers.
■ Synchronous mode Remote Copy is restored between InServ1 and InServ2.
Remote Copy Configuration
Loading...