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IBM System Storage SAN Volume Controller

Jon TateKatja Gebuhr

Kamalakkannan J JayaramanXiao Peng Zhao

Install, use, and troubleshoot the SAN Volume Controller

Learn how to implement block virtualization

Perform backup and restore on a cluster

International Technical Support Organization

IBM System Storage SAN Volume Controller

September 2007

SG24-6423-05

Copyright International Business Machines Corporation 2003-2007. All rights reserved.Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP ScheduleContract with IBM Corp.

Fifth Edition (September 2007)This edition applies to Version 4 Release 2 Modification 0 of the IBM System Storage SAN Volume Controller.

Note: Before using this information and the product it supports, read the information in Notices on page xiii.

Contents

Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiiiTrademarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xvThe team that wrote this Redbooks publication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviBecome a published author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xixComments welcome. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xx

Summary of changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiSeptember 2007, Fifth Edition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxi

Chapter 1. Introduction to storage virtualization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 The need for storage virtualization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2 In-band virtualization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.3 Out-of-band virtualization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1.3.1 IBM Global Parallel File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Chapter 2. IBM System Storage SAN Volume Controller overview . . . . . . . . . . . . . . . . 92.1 Maximum supported configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.2 Glossary of commonly used terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.3 Virtualization overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.4 Compass architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.4.1 SAN Volume Controller clustering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.4.2 SAN Volume Controller virtualization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.4.3 SAN Volume Controller multipathing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.5 SAN Volume Controller logical configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172.6 SAN Volume Controller compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182.7 Software licensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192.8 Whats new and whats in SVC 4.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Chapter 3. Planning and configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.1 General planning rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.2 Physical planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

3.2.1 Preparing your UPS environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293.2.2 Physical rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303.2.3 Cable connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

3.3 SAN planning and configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323.3.1 SAN definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333.3.2 Fibre Channel switches, fabrics, interswitch links, and hops . . . . . . . . . . . . . . . . 353.3.3 General design considerations with the SVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353.3.4 Boot support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393.3.5 Configuration saving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393.3.6 High availability SAN design and configuration rules with SVC . . . . . . . . . . . . . . 39

3.4 Zoning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403.5 Naming conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

3.5.1 Dual room high availability configuration with the SVC. . . . . . . . . . . . . . . . . . . . . 453.5.2 Local and remote SAN fabrics with SVC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463.5.3 Technologies for extending the distance between two SVC clusters . . . . . . . . . . 46 Copyright IBM Corp. 2003-2007. All rights reserved. iii

3.6 SVC disk subsystem planning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483.6.1 Block virtualization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503.6.2 MDGs, I/O groups, virtual disks, and managed disks . . . . . . . . . . . . . . . . . . . . . . 503.6.3 Extents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523.6.4 Image mode virtual disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523.6.5 Managed mode virtual disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 533.6.6 Allocation of free extents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553.6.7 Selecting MDGs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 563.6.8 I/O handling and offline conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 563.6.9 Quorum disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573.6.10 Virtualization operations on virtual disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 593.6.11 Creating an MDisk group (extent size rules) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 603.6.12 Creating a managed disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 613.6.13 Creating a virtual disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623.6.14 Quality of service on VDisk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 643.6.15 Creating an SVC host and mapping VDisks to that host. . . . . . . . . . . . . . . . . . . 643.6.16 Port masking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 643.6.17 Standard and persistent reserve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653.6.18 Expanding an SVC cluster configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653.6.19 Migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

3.7 SVC supported capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 653.7.1 Adding DS8000 storage to the SVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 663.7.2 Adding ESS storage to the SVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 713.7.3 Adding DS4000 storage to the SVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 763.7.4 LUN layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Chapter 4. Performance and capacity planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 814.1 Performance considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

4.1.1 SAN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 824.1.2 Disk subsystem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 834.1.3 SVC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 844.1.4 Host. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

4.2 Performance modeling and sizing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.3 Performance monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

4.3.1 Collecting performance statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.3.2 Cluster wide statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 914.3.3 Per-node statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Chapter 5. Master console . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 955.1 Master console overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

5.1.1 Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 975.1.2 Example hardware configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

5.2 Management console software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 985.3 Installation planning information for the master console . . . . . . . . . . . . . . . . . . . . . . . . 985.4 Secure Shell overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

5.4.1 Generating public and private SSH key pairs using PuTTY . . . . . . . . . . . . . . . . 1005.5 Basic installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

5.5.1 Creating the cluster (first time) using the service panel . . . . . . . . . . . . . . . . . . . 1045.6 Completing the initial cluster setup using the SAN Volume Controller Console GUI . 107

5.6.1 Configuring the GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1085.6.2 Uploading the SSH public key to the SVC cluster. . . . . . . . . . . . . . . . . . . . . . . . 1165.6.3 Uploading SSH public key(s) sample scenarios . . . . . . . . . . . . . . . . . . . . . . . . . 1205.6.4 Configuring the PuTTY session for the CLI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122iv IBM System Storage SAN Volume Controller

5.6.5 Starting the PuTTY CLI session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1255.7 Initial role-based authentication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1285.8 Upgrading the Master Console . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1295.9 Call Home (service alert). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135Chapter 6. Quickstart configuration using the CLI . . . . . . . . . . . . . . . . . . . . . . . . . . . 1396.1 Adding nodes to the cluster. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1406.2 Setting the cluster time zone and time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1426.3 Checking the license features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1436.4 Creating host definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1436.5 Displaying managed disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1466.6 Creating managed disk groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1476.7 Creating a virtual disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1486.8 Assigning a VDisk to a host . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

Chapter 7. Quickstart configuration using the GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . 1537.1 Adding nodes to the cluster. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

7.1.1 Installing certificates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1587.2 Setting the cluster time zone and time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1627.3 Checking the license status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1637.4 Creating host definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1647.5 Displaying managed disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1667.6 Creating managed disk groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1677.7 Creating a VDisk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1697.8 Assigning a VDisk to a host . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

Chapter 8. Host configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1818.1 SVC setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1828.2 Switch and zoning configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

8.2.1 Additional zoning considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1848.3 AIX-specific information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

8.3.1 Configuring the AIX host . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1858.3.2 Configuration information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1858.3.3 Host adapter configuration settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1868.3.4 SDD installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1878.3.5 Discovering the assigned VDisk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1888.3.6 Using SDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1918.3.7 Creating and preparing volumes for use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1928.3.8 Expanding an AIX volume. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1938.3.9 Removing an SVC volume on AIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1958.3.10 Running SVC commands from an AIX host system . . . . . . . . . . . . . . . . . . . . . 196

8.4 Windows-specific information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1968.4.1 Configuring Windows 2000 and Windows 2003 hosts . . . . . . . . . . . . . . . . . . . . 1978.4.2 Configuration information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1978.4.3 Host adapter installation and configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1978.4.4 SDD installation on Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1988.4.5 Windows 2003 and MPIO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1998.4.6 Subsystem Device Driver Device Specific Module (SDDDSM) for SVC. . . . . . . 1998.4.7 Discovering the assigned VDisk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2008.4.8 Expanding a Windows 2000/2003 volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2038.4.9 Removing a disk on Windows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2108.4.10 Using SDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2138.4.11 Running an SVC command line (CLI) from a Windows host system . . . . . . . . 214 Contents v

8.5 Microsoft Volume Shadow Copy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2148.5.1 Installation overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2158.5.2 System requirements for the IBM System Storage hardware provider . . . . . . . . 2158.5.3 Installing the IBM System Storage hardware provider . . . . . . . . . . . . . . . . . . . . 2168.5.4 Verifying the installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2258.5.5 Creating the free and reserved pools of volumes . . . . . . . . . . . . . . . . . . . . . . . . 225

8.6 Linux (on Intel) specific information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2278.6.1 Configuring the Linux host . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2278.6.2 Configuration information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2278.6.3 Host adapter configuration settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2278.6.4 Discovering the assigned VDisk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2288.6.5 Using SDD on Linux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2288.6.6 Creating and preparing volumes for use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

8.7 SUN Solaris support information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2348.7.1 Operating system versions and maintenance levels. . . . . . . . . . . . . . . . . . . . . . 2348.7.2 Multipath configurations supported . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2348.7.3 SDD dynamic pathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234

8.8 HP-UX configuration information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2358.9 VMware configuration information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237

8.9.1 Operating system versions and maintenance levels. . . . . . . . . . . . . . . . . . . . . . 2378.9.2 Multipath solutions supported . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237

8.10 More information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

Chapter 9. SVC configuration and administration using the CLI . . . . . . . . . . . . . . . . 2399.1 Managing user-roles using the CLI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240

9.1.1 Role-based security commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2409.2 Managing the cluster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

9.2.1 Organizing on-screen content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2429.2.2 Viewing cluster properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2449.2.3 Maintaining passwords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2459.2.4 Modifying IP addresses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2459.2.5 Setting the cluster time zone and time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2469.2.6 Starting a statistics collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2479.2.7 Stopping a statistics collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2489.2.8 Audit Log commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2489.2.9 Status of discovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2499.2.10 Status of copy operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2509.2.11 Shutting down a cluster. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250

9.3 Working with nodes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2519.3.1 I/O groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2519.3.2 Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253

9.4 Working with managed disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2569.4.1 Disk controller systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2569.4.2 Managed disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2579.4.3 Managed Disk Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264

9.5 Working with virtual disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2679.5.1 Hosts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2679.5.2 Virtual disks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2749.5.3 Tracing a host disk back to its source physical disk . . . . . . . . . . . . . . . . . . . . . . 284

9.6 Managing copy services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2869.7 Service and maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286

9.7.1 Upgrading software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2869.7.2 Running maintenance procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291vi IBM System Storage SAN Volume Controller

9.7.3 Setting up error notification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2939.7.4 Analyzing the error log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2939.7.5 License settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2949.7.6 Viewing the feature log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

9.8 SVC cluster configuration backup and recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2969.8.1 Backing up the SVC cluster configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2979.8.2 Restoring the SVC cluster configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2999.8.3 Deleting configuration backup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299

9.9 Listing dumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3009.10 T3 recovery process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3049.11 Scripting and its usage under CLI for SVC task automation . . . . . . . . . . . . . . . . . . . 304

Chapter 10. SVC configuration and administration using the GUI. . . . . . . . . . . . . . . 30510.1 Managing user-roles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306

10.1.1 Creating a user-role using the GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30610.1.2 Modifying a user-role . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31110.1.3 Deleting a user-role. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314

10.2 Managing the cluster using the GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31510.2.1 Organizing on-screen content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31510.2.2 Viewing cluster properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32310.2.3 Maintain Cluster Passwords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32310.2.4 Modifying IP Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32410.2.5 Setting the cluster time zone and time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32610.2.6 Starting the statistics collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32710.2.7 Stopping the statistics collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32810.2.8 Shutting down a cluster. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

10.3 Working with nodes using the GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33010.3.1 I/O groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33010.3.2 Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332

10.4 Viewing progress. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33710.5 Working with managed disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337

10.5.1 Disk controller systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33810.5.2 Discovery status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34010.5.3 Managed disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34010.5.4 Managed Disk Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352

10.6 Working with hosts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36110.6.1 Hosts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36210.6.2 Fabrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373

10.7 Working with virtual disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37410.7.1 Using the Virtual Disks panel for VDisks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37410.7.2 Showing VDisks mapped to a host . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394

10.8 Managing Copy Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39610.9 Service and maintenance using the GUI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396

10.9.1 Upgrading software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39610.9.2 Running maintenance procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40510.9.3 Setting error notification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40810.9.4 Analyzing the error log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41010.9.5 License settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41310.9.6 Viewing the license settings log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41510.9.7 Listing dumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416

10.10 Backing up the SVC configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42010.10.1 Backup procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42110.10.2 Restoring the SVC configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422 Contents vii

10.10.3 Deleting the configuration backup files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 423

Chapter 11. Copy Services: FlashCopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42511.1 FlashCopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42611.2 SVC FlashCopy features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42711.3 How it works . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428

11.3.1 FlashCopy mappings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42911.3.2 Multi-Target FlashCopy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43011.3.3 Consistency groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43111.3.4 FlashCopy indirection layer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43311.3.5 Interaction and dependency between MTFC . . . . . . . . . . . . . . . . . . . . . . . . . . 43611.3.6 Summary of the FlashCopy indirection layer algorithm. . . . . . . . . . . . . . . . . . . 43811.3.7 Interaction with the cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43811.3.8 FlashCopy rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43911.3.9 FlashCopy and image mode disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43911.3.10 FlashCopy mapping events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44011.3.11 FlashCopy mapping states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44311.3.12 Background copy rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44611.3.13 Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44711.3.14 Serialization of I/O by FlashCopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44711.3.15 Error handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44711.3.16 Asynchronous notifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44911.3.17 Interoperation with Metro Mirror and Global Mirror . . . . . . . . . . . . . . . . . . . . . 44911.3.18 Recovering data from FlashCopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 449

11.4 Using Command Line to do FlashCopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45011.4.1 Scenario description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45011.4.2 Creating a FlashCopy consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45111.4.3 Creating a FlashCopy mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45211.4.4 Preparing (pre-triggering) the FlashCopy mapping. . . . . . . . . . . . . . . . . . . . . . 45311.4.5 Preparing (pre-triggering) the FlashCopy consistency group . . . . . . . . . . . . . . 45411.4.6 Starting (triggering) FlashCopy mappings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45511.4.7 Starting (triggering) FlashCopy consistency group . . . . . . . . . . . . . . . . . . . . . . 45511.4.8 Monitoring the FlashCopy progress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45611.4.9 Deleting the FlashCopy mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45611.4.10 Deleting the FlashCopy consistency group. . . . . . . . . . . . . . . . . . . . . . . . . . . 45711.4.11 Stopping the FlashCopy mapping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45711.4.12 Stopping the FlashCopy consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . 458

11.5 Using the GUI to perform FlashCopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45911.5.1 Creating a FlashCopy consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45911.5.2 Creating a FlashCopy mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46111.5.3 Preparing (pre-triggering) the FlashCopy mapping. . . . . . . . . . . . . . . . . . . . . . 47011.5.4 Preparing (pre-triggering) the FlashCopy consistency group . . . . . . . . . . . . . . 47211.5.5 Starting (triggering) FlashCopy mappings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47311.5.6 Starting (triggering) FlashCopy consistency group . . . . . . . . . . . . . . . . . . . . . . 47411.5.7 Monitoring the FlashCopy progress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47511.5.8 Deleting the FlashCopy mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47611.5.9 Deleting the FlashCopy consistency group. . . . . . . . . . . . . . . . . . . . . . . . . . . . 47711.5.10 Stopping the FlashCopy/Consistency group. . . . . . . . . . . . . . . . . . . . . . . . . . 479

Chapter 12. Copy Services: Metro Mirror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48112.1 Metro Mirror. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 482

12.1.1 Metro Mirror overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48212.1.2 Supported methods for synchronizing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483viii IBM System Storage SAN Volume Controller

12.1.3 The importance of write ordering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48412.1.4 Practical use of Metro Mirror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48612.1.5 SVC Metro Mirror features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48712.1.6 Metro Mirror states and events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49112.1.7 Metro Mirror configuration limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495

12.2 Metro Mirror commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49512.2.1 Listing available SVC cluster partners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49612.2.2 Creating SVC cluster partnership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49612.2.3 Creating a Metro Mirror consistency group. . . . . . . . . . . . . . . . . . . . . . . . . . . . 49712.2.4 Creating a Metro Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49712.2.5 Changing a Metro Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49812.2.6 Changing a Metro Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . . 49812.2.7 Starting a Metro Mirror relationship. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49812.2.8 Stopping a Metro Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49912.2.9 Starting a Metro Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49912.2.10 Stopping a Metro Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . 49912.2.11 Deleting a Metro Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50012.2.12 Deleting a Metro Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . . 50012.2.13 Reversing a Metro Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50012.2.14 Reversing a Metro Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . 50112.2.15 Detailed states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50112.2.16 Background copy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504

12.3 Metro Mirror scenario using the CLI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50512.4 Metro Mirror scenario using the GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517

12.4.1 Setting up Metro Mirror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 518

Chapter 13. Copy Services: Global Mirror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54713.1 Global Mirror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 548

13.1.1 Supported methods for synchronizing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55013.1.2 The importance of write ordering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55113.1.3 Using Global Mirror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55213.1.4 SVC Global Mirror features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553

13.2 How Global Mirror works. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55413.2.1 Intercluster communication and zoning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55413.2.2 Global Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55513.2.3 Global Mirror consistency groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55613.2.4 Global Mirror states and events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55713.2.5 Global Mirror configuration limits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 561

13.3 Global Mirror commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56113.3.1 Listing available SVC cluster partners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56213.3.2 Creating an SVC cluster partnership. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56213.3.3 Creating a Global Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . . 56313.3.4 Creating a Global Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56413.3.5 Changing a Global Mirror relationship. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56413.3.6 Changing a Global Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . 56513.3.7 Starting a Global Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56513.3.8 Stopping a Global Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56513.3.9 Starting a Global Mirror consistency group. . . . . . . . . . . . . . . . . . . . . . . . . . . . 56613.3.10 Stopping a Global Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . 56613.3.11 Deleting a Global Mirror relationship. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56613.3.12 Deleting a Global Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . 56713.3.13 Reversing a Global Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56713.3.14 Reversing a Global Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . 567 Contents ix

13.3.15 Detailed states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56813.3.16 Background copy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571

13.4 Global Mirror scenario using the CLI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57113.4.1 Setting up Global Mirror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57213.4.2 Creating an SVC partnership between ITSOSVC42A and ITSOSVC42B . . . . 57313.4.3 Changing link tolerance and cluster delay simulation . . . . . . . . . . . . . . . . . . . . 57413.4.4 Executing Global Mirror. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 576

13.5 Global Mirror scenario using the GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58413.5.1 Setting up Global Mirror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58513.5.2 Creating an SVC partnership between ITSOSVC42A and ITSOSVC42B . . . . 58513.5.3 Creating a Global Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . . 59013.5.4 Creating the Global Mirror relationships for VDISK1 and VDISK2 . . . . . . . . . . 59313.5.5 Creating the stand-alone Global Mirror relationship for VDISK3. . . . . . . . . . . . 59813.5.6 Executing Global Mirror. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60313.5.7 Starting a stand-alone Global Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . 60313.5.8 Starting a Global Mirror consistency group. . . . . . . . . . . . . . . . . . . . . . . . . . . . 60513.5.9 Stopping a stand-alone Global Mirror relationship . . . . . . . . . . . . . . . . . . . . . . 60713.5.10 Stopping a Global Mirror consistency group . . . . . . . . . . . . . . . . . . . . . . . . . . 60813.5.11 Restarting a Global Mirror relationship in the Idling state . . . . . . . . . . . . . . . . 61013.5.12 Restarting a Global Mirror consistency group in the Idling state. . . . . . . . . . . 61213.5.13 Switching copy direction for a Global Mirror relationship . . . . . . . . . . . . . . . . 61313.5.14 Switching copy direction for a Global Mirror consistency group . . . . . . . . . . . 615

Chapter 14. Migration to and from the SAN Volume Controller . . . . . . . . . . . . . . . . . 61714.1 Migration overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61814.2 Migration operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 618

14.2.1 Migrating multiple extents (within an MDG) . . . . . . . . . . . . . . . . . . . . . . . . . . . 61814.2.2 Migrating extents off an MDisk that is being deleted. . . . . . . . . . . . . . . . . . . . . 61914.2.3 Migrating a VDisk between MDGs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62014.2.4 Migrating the VDisk to image mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62214.2.5 Migrating a VDisk between I/O groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62214.2.6 Monitoring the migration progress. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623

14.3 Functional overview of migration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62414.3.1 Parallelism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62414.3.2 Error handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62414.3.3 Migration algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625

14.4 Migrating data from an image mode VDisk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62614.4.1 Image mode VDisk migration concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62614.4.2 Migration tips. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 628

14.5 Data migration for Windows using the GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62814.5.1 Windows 2000 host system connected directly to the DS4500 . . . . . . . . . . . . 62914.5.2 SVC added between the Windows 2000 host system and the ESS . . . . . . . . . 63114.5.3 Migrating the VDisk from image mode to managed mode . . . . . . . . . . . . . . . . 64014.5.4 Migrating the VDisk from managed mode to image mode . . . . . . . . . . . . . . . . 64414.5.5 Migrating the VDisk from image mode to image mode . . . . . . . . . . . . . . . . . . . 648

14.6 Migrating Linux SAN disks to SVC disks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65114.6.1 Connecting the SVC to your SAN fabric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65314.6.2 Prepare your SVC to virtualize disks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65414.6.3 Move the LUNs to the SVC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65714.6.4 Migrate the image mode VDisks to managed MDisks . . . . . . . . . . . . . . . . . . . 66014.6.5 Preparing to migrate from the SVC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66114.6.6 Migrate the VDisks to image mode VDisks. . . . . . . . . . . . . . . . . . . . . . . . . . . . 66414.6.7 Remove the LUNs from the SVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 665x IBM System Storage SAN Volume Controller

14.7 Migrating ESX SAN disks to SVC disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66814.7.1 Connecting the SVC to your SAN fabric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67014.7.2 Prepare your SVC to virtualize disks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67114.7.3 Move the LUNs to the SVC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67414.7.4 Migrate the image mode VDisks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67814.7.5 Preparing to migrate from the SVC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68014.7.6 Migrate the managed VDisks to image mode VDisks . . . . . . . . . . . . . . . . . . . . 68314.7.7 Remove the LUNs from the SVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 683

14.8 Migrating AIX SAN disks to SVC disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68814.8.1 Connecting the SVC to your SAN fabric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69014.8.2 Prepare your SVC to virtualize disks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69114.8.3 Move the LUNs to the SVC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69414.8.4 Migrate the image mode VDisks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69714.8.5 Preparing to migrate from the SVC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69814.8.6 Migrate the managed VDisks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70014.8.7 Remove the LUNs from the SVC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 701

Appendix A. Copy services and open systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 705AIX specifics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 706

AIX and FlashCopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 706AIX and Metro Mirror and Global Mirror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 711Making updates to the LVM information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 712

Windows NT and 2000/2003 specifics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 713Windows NT and Copy Services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 713Copy Services with Windows Volume Sets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 715Windows 2000/2003 and Copy Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 718 Contents xi

Appendix B. DS4000 migration scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 731Initial considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 732Scenario 1: Total number of LUNs is less than maximum LUNs per partition . . . . . . . . . . 733Scenario 2: Total number of LUNs is more than maximum LUNs per partition . . . . . . . . . 738

Appendix C. Scripting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 745Scripting structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 746Automated VDisk creation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 747SVC tree. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 749Scripting alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 756

Appendix D. Node replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 757Replacing nodes non-disruptively . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 758Replacing nodes disruptively (rezoning the SAN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 760Replacing nodes disruptively (moving VDisks to new I/O group). . . . . . . . . . . . . . . . . . . . 762Appendix E. HPUX11i Metro Mirror using PVlinks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 763

Appendix F. HPUX11i Metro Mirror with SDD vpath devices . . . . . . . . . . . . . . . . . . . 769Summary of activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 769Preparation for Metro Mirror . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 772Start the Metro Mirror relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 773

Related publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 777IBM Redbooks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 777

Other resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 777Referenced Web sites. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 778

How to get IBM Redbooks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 778IBM Redbooks collections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 778

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 779xii IBM System Storage SAN Volume Controller

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This information contains sample application programs in source language, which illustrate programming techniques on various operating platforms. You may copy, modify, and distribute these sample programs in any form without payment to IBM, for the purposes of developing, using, marketing or distributing application programs conforming to the application programming interface for the operating platform for which the sample programs are written. These examples have not been thoroughly tested under all conditions. IBM, therefore, cannot guarantee or imply reliability, serviceability, or function of these programs. Copyright IBM Corp. 2003-2007. All rights reserved. xiii

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Linux is a trademark of Linus Torvalds in the United States, other countries, or both.

Other company, product, or service names may be trademarks or service marks of others. xiv IBM System Storage SAN Volume Controller

Preface

This IBM Redbooks publication is a detailed technical guide to the IBM System Storage SAN Volume Controller (SVC), a virtualization appliance solution that maps virtualized volumes visible to hosts and applications to physical volumes on storage devices. Each server within the SAN has its own set of virtual storage addresses, which are mapped to physical addresses. If the physical addresses change, the server continues running using the same virtual addresses that it had before. This means that volumes or storage can be added or moved while the server is still running. The IBM virtualization technology improves management of information at the block level in a network, enabling applications and servers to share storage devices on a network.

Successful businesses require real-time responsiveness to change, whether because of new customer needs, changes in the supply chain, unexpected competitive moves, external threats, or changes in the economic climate. Rapid response to change requires an IT infrastructure that can turn information into a competitive advantage; the IT infrastructure must provide the maximum benefit at an affordable cost, and must have the flexibility to support changes in business processes. An on demand operating environment provides a cost effective and flexible IT environment. With information at the heart of competitiveness, storage becomes an ever more critical component of an on demand operating environment.

The IBM System Storage strategy addresses some of the most pressing needs currently facing Chief Information Officers (CIO) and IT managers. As part of its strategy, IBM intends to deliver industry leading technologies that will help dramatically reduce the total cost of ownership (TCO) for storage, and help turn fixed costs into variable costs that scale with business volume.

Success in the on demand world will depend on the ability to leverage information technology. A greater dependence on information means a greater dependence on storage. What distinguishes an on demand business is the ability to quickly sense and rapidly respond to a dynamic marketplace; to do this, there are challenges that an on demand business must overcome.

At the business level, customers are faced with three major storage challenges: Managing storage growth: Storage needs to continue to grow at over 50% per year.

Managing storage is becoming more complex than ever, because we now have to deal with multiple server platforms and different operating systems, which may be connected to a storage area network (SAN) with multiple and diverse storage platforms.

Increasing complexity: Although the declining cost of storage per megabyte makes it attractive to add additional disks, the increasing complexity of managing this storage results in over-utilized staff and under-utilized IT resources. Combining this with the shortage of skilled storage administrators, it is possible to add significant cost and introduce risk to storage management.

Maintaining availability: The added complexity of 24x7 environments significantly reduces, for example, the efficiency of conducting routine maintenance, scheduling backups, data migration, and introducing new software and hardware. This problem is compounded by the fact that as availability increases, so does the cost inherent with making it so.

Variety of information: Information Technology holds the promise of bringing a variety of new types of information to the people who need it. Copyright IBM Corp. 2003-2007. All rights reserved. xv

Volume of data: Data is growing exponentially. Estimates show a continued 60% yearly growth of new disk in petabytes shipped.

Velocity of change: IT Organizations are under tremendous pressure to deliver the right IT services. Approximately 85% of problems are caused by IT staff changing something, and 80% of problems are not detected by IT staff until reported.

These challenges still exist, although large SANs do offer desirable and tangible benefits, for example, better connectivity, improved performance, distance flexibility, and scalability. However, even these benefits may be outweighed by the added complexity that they introduce.

As an example, large enterprise SANs often contain different types of storage devices. These differences could be in the types of disk deployed, their level of performance, or the functionality provided, such as RAID or mirroring. Often, customers have different vendor storage devices as the result of mergers or consolidations. The result, however, is that storage and SAN administrators need to configure storage to servers, and then keep track of which servers own or have access to that storage. The storage administrative tasks can become daunting as the SAN grows and as the storage administrators manually attempt to manage the SAN.

Furthermore, the complexity of having different file systems in the same SAN requires that storage administrators know how to administer each client operating system (OS) platform. The management interfaces for each may be different, since there is no common standard that all vendors adhere to. Lastly, since the file systems are tied to each of the servers, storage management functions potentially have to be run on hundreds of servers. It is easy to see why manageability and interoperability are the top areas for concern, especially in a SAN where the number of possible storage and OS platform permutations is considerable.

These challenges are at odds with the commonly held belief that storage is decreasing in cost per megabyte. It is clear that the cost of managing storage is greater than the initial purchase price. A product is needed to address storage manageability, while at the same time addressing the need for interoperability. This product is the focus of this book.

The team that wrote this Redbooks publicationThis Redbooks publication was produced by a team of specialists working at the ITSO in the San Jose Center, San Jose, California.xvi IBM System Storage SAN Volume Controller

Front L-R, Katja, Kamal; rear L-R, Jon, Heidi

Jon Tate is a Project Manager for IBM System Storage SAN Solutions at the International Technical Support Organization, San Jose Center. Before joining the ITSO in 1999, he worked in the IBM Technical Support Center, providing Level 2 support for IBM storage products. Jon has 20 years of experience in storage software and management, services, and support, and is both an IBM Certified IT Specialist and an IBM SAN Certified Specialist.

Katja Gebuhr is a System Support Specialist for the SAN Volume Controller and SAN products working for csg Germany in Mainz. She joined csg in 2006 after finishing her IT-System businessman apprenticeship at the IBM Germany in Mainz. Katja is currently working in the DASD FrontEnd SAN Support Team and provides Level 1 Hardware and Software support for IMT Germany and CEMAAS.

Kamalakkannan J Jayaraman (Kamal) is an IT specialist working for IBM India. His areas of expertise include Multivendor Disk, Tape Solutions, UNIX, and Windows Operating Systems. His current job includes designing and implementing storage solutions and his areas of interest include storage virtualization and multi-site replication. He has participated in multiple storage technical talks and storage forums.

Xiao Peng Zhao (Heidi) is an Advisory IT Specialist for Storage ATS in IBM China. She has four years experience in planning, managing, designing, implementing, problem analysis, and tuning the IBM SAN Volume Controller. Her areas of expertise include Open Systems, Disk Subsystems, SAN fabrics, and NAS.

We extend our thanks to the following people for their contributions to this project. Preface xvii

There are many people that contributed to this book. In particular, we thank the development and PFE teams in Hursley. Matt Smith was also instrumental in moving any issues along and ensuring that they maintained a high profile.

In particular, we thank the previous authors of this redbook:Matt Amanat Angelo BernasconiSteve CodySean CrawfordDeon GeorgeAmarnath HiriyannappaThorsten HossPhilippe JachimczykBent LeragerCraig McKennaAndy McManusJoao Marcos LeiteBarry MellishMassimo RosatiFred ScholtenRobert SymonsMarcus Thordal

We would also like to thank the following people for their contributions:

Doris KoniecznyIBM Tucson

John AgombarAlex AinscowIain BethuneTrevor BoardmanChris CantoPeter EcclesCarlos FuenteBob GraingerMargaret HillAlex HowellGary JarmanColin JewellStuart JonesSimon LinfordAndrew MartinPaul MasonRichard MawsonPaul MerrisonRob NicholsonNick OLearySteve RandleLucy RawBill ScalesDave SinclairMatt SmithSteve WhiteBarry Whytexviii IBM System Storage SAN Volume Controller

IBM Hursley

Bill WiegandIBM Advanced Technical Support

Timothy CrawfordScott FaddenRoss HagglundIBM Beaverton

Dorothy FaurotIBM Raleigh

Craig GordonIBM Gaithersburg

John GressettIBM Rochester

Chris SaulIBM San Jose

Che Lui (Shirley) ShumIBM San Jose

Sharon WangIBM Chicago

Craig McKennaIBM Australia

Tom CadyDeanna PolmSangam RacherlaYvonne LyonIBM ITSO

Tom and Jenny ChangGarden Inn Hotel, Los Gatos, California

Become a published authorJoin us for a two- to six-week residency program! Help write a Redbooks publication dealing with specific products or solutions, while getting hands-on experience with leading-edge technologies. You'll team with IBM technical professionals, Business Partners and/or clients.

Your efforts will help increase product acceptance and client satisfaction. As a bonus, you'll develop a network of contacts in IBM development labs, and increase your productivity and marketability.

Find out more about the residency program, browse the residency index, and apply online at:ibm.com/redbooks/residencies.html Preface xix

Comments welcomeYour comments are important to us!

We want our Redbooks to be as helpful as possible. Send us your comments about this or other Redbooks in one of the following ways: Use the online Contact us review redbook form found at:

ibm.com/redbooks

Send your comments in an e-mail to:redbook@us.ibm.com

Mail your comments to:IBM Corporation, International Technical Support OrganizationDept. HYTD Mail Station P0992455 South RoadPoughkeepsie, NY 12601-5400xx IBM System Storage SAN Volume Controller

Summary of changes

This section describes the technical changes made in this edition of the book and in previous editions. This edition may also include minor corrections and editorial changes that are not identified.

Summary of Changesfor SG24-6423-05for IBM System Storage SAN Volume Controlleras created or updated on September 10, 2007.

September 2007, Fifth EditionThis revision reflects the addition, deletion, or modification of new and changed information described below.

New information Added Multi Target FlashCopy Auto-delete of FlashCopy mapping Role based security

Changed information Numerous screen captures and their descriptions Copyright IBM Corp. 2003-2007. All rights reserved. xxi

xxii IBM System Storage SAN Volume Controller

Chapter 1. Introduction to storage virtualization

In this chapter we describe the need for storage virtualization and the IBM approach to both in-band and out-of-band storage virtualization. The fundamental differences between the two architectures are articulated to explain why IBM has chosen to use in-band virtualization for the IBM System Storage SAN Volume Controller (the focus of the remainder of this book).

1 Copyright IBM Corp. 2003-2007. All rights reserved. 1

1.1 The need for storage virtualizationAt the business level, clients are faced with three major storage challenges: Managing storage growth: Storage needs continue to grow at a rate that is normally

higher than what has been planned for each year. As an example, storage subsystems can be purchased to last for 3 to 5 years, however, organizations are finding that they are filling to capacity much earlier than that.To fill the growth, customers are then either extending their current storage subsystems in chunks, or buying different types of storage subsystems to match their storage needs and budget.

Increasing complexity: As storage needs grow, this need can be filled by more than one disk subsystem, which might not even be from the same vendor.Together with the variety of server platforms and operating systems in a customers environment, customers can have storage area networks (SAN) with multiple and diverse storage subsystems and host platforms.Combining this with the shortage of skilled storage administrators, the cost and risk of storage increases as the environment becomes more complex.

Maintaining availability: With the increased range of storage options available, the storage growth rate, and no similar increase in storage budget, customers are facing having to manage more storage with minimal or no additional staff.Thus, with the complexity highlighted above, and with business requirements on IT resources towards higher business system availability, the room for errors increases as each new storage subsystem is added to the infrastructure.Additionally, making changes to the storage infrastructure to accommodate storage growth traditionally leads to outages that might not be acceptable by the business.

Storage needs are rising, and the challenge of managing disparate storage systems is growing. The IBM System Storage SAN Volume Controller brings storage devices together in a virtual pool to make all storage appear as: One logical device to centrally manage and to allocate capacity as needed One solution to help achieve the most effective use of key storage resources on demand

Virtualization solutions can be implemented in the storage network, in the server, or in the storage device itself. The IBM storage virtualization solution is SAN-based, which helps allow for a more open virtualization implementation. Locating virtualization in the SAN, and therefore in the path of input/output (I/O) activity, helps to provide a solid basis for policy-based management. The focus of IBM on open standards means its virtualization solution supports freedom of choice in storage-device vendor selection.

The IBM System Storage SAN Volume Controller solution is designed to: Simplify storage management Reduce IT data storage complexity and costs while enhancing scalability Extend on-demand flexibility and resiliency to the IT infrastructure Increase application availability by making changes in the infrastructure without having to

shut down hosts2 IBM System Storage SAN Volume Controller

1.2 In-band virtualizationIn a conventional SAN, the logical unit numbers (LUNs) that are defined within the storage subsystem are directly presented to the host or hosts. In-band virtualization, otherwise known as block aggregation, essentially means having an appliance in the data path that can take physical storage from one or more storage subsystems and offer it to hosts in the form of a virtual disk (VDisk).The Storage Networking Industry Association (SNIA) Block Aggregation Model (Figure 1-1) specifies that block aggregation can be performed within hosts (servers), in the storage network (storage routers, storage controllers), or in storage devices (intelligent disk arrays).

Figure 1-1 SNIA Block Aggregation Model

While each of these approaches has pros and cons and all are available in various forms from various vendors, IBM chose to develop its latest block aggregation product (IBM System Storage SAN Volume Controller) within the storage network.Block aggregation within the storage network provides four significant benefits to clients: Increased storage administrator productivity:

Administrators can manage, add, and migrate physical disks non-disruptively from an application server point of view. This is accomplished by providing insulation between the servers view of the logical disks and the disks as presented by the storage subsystem. Productivity is improved by allowing administrators to perform management functions when convenient rather than waiting for ever decreasing maintenance windows. Downtime requirements are almost eliminated.

Copyright 2000, Storage Network Industry Association

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Host-based block aggregationHost-based block aggregationChapter 1. Introduction to storage virtualization 3

Providing a common platform for advanced functions:By providing a logical view of physical storage, advanced functions like disaster recovery can be done at a single point in the SAN in a consistent way regardless of the underlying physical storage. FlashCopy, Metro Mirror formerly referred to as Peer-to-Peer Remote Copy (PPRC) and data migration can also be performed in a consistent way. This common platform is used to provide other advanced functions over time such as advanced security and quality of service (QoS) capabilities.

Improved capacity utilization:Spare capacity on underlying physical disks can be reallocated non-disruptively from an application server point of view irrespective of the server operating system or platform type. Logical disks can be created from any of the physical disks being managed by the virtualization device (that is, vendor agnostic).

Simplification of connectivity:Each vendor storage subsystem would traditionally require a vendors device driver on the host to access the subsystem.Where there are many subsystems in the environment, regardless of whether any one host is accessing more than one vendors storage subsystems, then managing the range of device drivers is unnecessarily complex.The IBM approach means that only one device driver, the IBM System Storage Subsystem Device Driver (SDD), is required to access any virtualized storage on the SAN regardless of the vendor storage subsystem.

Figure 1-2 shows the IBM approach to block aggregation.

Figure 1-2 IBM plan for block aggregation4 IBM System Storage SAN Volume Controller

In addition to the four major benefits outlined above, abstracting the hosts from directly accessing the storage subsystem or subsystems has many other benefits over other methods of block aggregation, including these: It provides the ability to add advanced functions and apply them to the entire storage

infrastructure. The first release of the product offered these functions: Copy Services (Metro Mirror (formerly referred to as PPRC) and FlashCopy) Data migration Read and Write Caching

Later releases of the product offer such functions as: Quality of Service Performance based data migration Performance optimization in the data path Advanced security Copy Services: Global Mirror

It does not lock a client into a particular storage hardware vendor. It is not intrusive on the hosts. It can offload function from the hosts. It can support storage management from multiple ISVs. It offers superior scalability.

The IBM virtualization product provides redundant, modular, and scalable solutions. It is based on a clustered IBM SAN appliance running a Linux kernel to support high availability and performance. Additional nodes are capable of being added non-disruptively providing enterprise class scalability. IBMs long history of storage controller development has enabled us to develop systems where, in the exceptionally rare case that a failure occurs, the virtualization device can fail and recover gracefully. Figure 1-3 shows a representation of the IBM System Storage SAN Volume Controller.

Figure 1-3 Conceptual diagram of the IBM SAN Volume Controller Chapter 1. Introduction to storage virtualization 5

In summary, enterprise class block aggregation functionality is added to the storage network. The IBM solution improves storage administrator productivity, provides a common base for advanced functions, and provides for more efficient use of storage. The IBM product is designed to be delivered as a horizontally scalable, integrated solution based on the IBM SAN appliance, and Linux, using a fault tolerant clustered architecture.

1.3 Out-of-band virtualizationOut-of-band virtualization, otherwise known as file aggregation, is when the virtualization appliance is not in the data path. Typically, out-of-band virtualization is more geared toward file sharing across the SAN. To this end, it typically involves a single file system in a single name space.

File aggregation is a similar technique as block aggregation. However, rather than dealing with blocks of data, file aggregation addresses the needs of accessing and sharing files in a storage network. In the SNIA model, hosts get file metadata from file system or Network Attached Storage (NAS) controllers, and then access the data directly. File aggregation can be used in conjunction with or independent from block aggregation. Figure 1-4 shows the SNIA file aggregation model.

Figure 1-4 SNIA file aggregation model

1.3.1 IBM Global Parallel File SystemThe IBM approach to file virtualization is through the use of a common file system based on the IBM Global Parallel File System (GPFS). GPFS is a high-performance shared-disk cluster file system. GPFS provides concurrent high-speed file access to applications executing on multiple nodes of an AIX 5L cluster, a Linux cluster, or a heterogeneous cluster of AIX 5L and Linux nodes. In addition to providing file system storage capabilities, GPFS provides tools for management and administration of the GPFS cluster and allows for 6 IBM System Storage SAN Volume Controller

shared access to file systems from remote GPFS clusters.

GPFS provides scalable high-performance data access from a single node to 2,000 nodes or more. Up to 512 Linux nodes or 128 AIX 5L nodes with access to one or more file systems are supported as a general statement and larger configurations exist by special arrangements with IBM.

A GPFS file system is built from a collection of disks that contain the file system data and metadata. A file system can be built from a single disk or contain thousands of disks, each up to 2 terabytes in size, storing petabytes of data.

GPFS provides file level virtualization through a rule based policy engine. Data from files in a in a single directory can reside in one or across several storage pools. Determination of which storage pool the file data is initially written to, and how it is migrated, mirrored, or deleted over its life span, is based on a set of business rules in an administrator defined policy.

GPFS enables file level virtualization. This allows clients to reap the benefit of better application business responsiveness, maximized storage utilization, dynamic resource allocation, improved storage administration utilization, and reduced storage outage.

For greater detail about the technology and implementation of GPFS, see the white paper, An Introduction to GPFS, at:

http://www-03.ibm.com/systems/clusters/software/whitepapers/gpfs_intro.html

1.4 ConclusionIn conclusion, the IBM System Storage SAN Volume Controller enables storage virtualization. This allows clients to reap the benefit of better application business responsiveness, maximized storage utilization, dynamic resource allocation, improved storage administration utilization, and reduced storage outage.

In-band and out-of-band virtualization provide two very distinct yet complementary approaches to virtualization. IBM will extol the virtues of each in two separate products. Both products fulfill different requirements, and therefore they use different approaches to virtualization.

The rest of this book is dedicated to the IBM System Storage SAN Volume Controller and its method of in-band virtualization.

Note: Effective April 20, 2007, IBM withdrew from marketing the SAN File System. Its replacement is GPFS.Chapter 1. Introduction to storage virtualization 7

8 IBM System Storage SAN Volume Controller

Chapter 2. IBM System Storage SAN Volume Controller overview

In this chapter we describe the major concepts behind the IBM System Storage SAN Volume Controller to provide the framework for discussion for the remainder of this book.

2 Copyright IBM Corp. 2003-2007. All rights reserved. 9

2.1 Maximum supported configurationsFor a list of the maximum supported configurations, visit the SVC support site: http://www-304.ibm.com/jct01004c/systems/support/supportsite.wss/storageselectproduct?brandind=5000033&familyind=5329743&continue.x=9&continue.y=13&oldfamily=0

2.2 Glossary of commonly used termsBefore providing an overview of the IBM System Storage SAN Volume Controller, we begin this chapter with a short glossary of terms (in alphabetical order) most commonly used throughout this book.

Boss nodeA single node acts as the boss node for overall management of the cluster. If the boss node fails, another node in the cluster will take over the role.

Configuration nodeWhile the cluster is operational, a single node in the cluster is appointed to provide configuration and service functions over the network interface. This node is termed the configuration node. This configuration node manages a cache of the configuration information that describes the cluster configuration and provides a focal point for configuration commands. Similarly, at any one time, a single node acts as the boss node for overall management of the cluster. If the configuration node fails, another node in the cluster will assume the role.

ExtentEach managed disk in a managed disk group (MDG) is broken up logically into a number of extents. An extent is a number of contiguous logical blocks. A managed disk does not need to be an integer multiple of the extent size. The way this situation is handled is different depending on whether the managed disk is being used in Image Mode or Managed Mode. An extent is a fixed size unit of data that is used to manage the mapping of data between MDisks and VDisks.

Front-end and back-endThe SAN Volume Controller takes managed disks and presents these to application servers (hosts). The managed disks are looked after by the back-end application of the SAN Volume Controller. The virtual disks presented to hosts are looked after by the front-end application in the SAN Volume Controller.

GrainA grain is the unit of data represented by a single bit in a FlashCopy bitmap, 256 KB in the SAN Volume Controller.

I/O groupAn input/output (I/O) group contains two SAN Volume Controller nodes defined by the configuration process. Each SAN Volume Controller node is associated with exactly one I/O group. The nodes in the I/O group provide access to the VDisks in the I/O group.

LU and LUNStrictly speaking, there is a difference between a logical unit (LU) and a logical unit number 10 IBM System Storage SAN Volume Controller

(LUN). A LUN is a unique identifier used on a SCSI bus that enables it to differentiate

between devices (each of which is a logical unit). Each of the LUs in the SVC is an MDisk. In practice, the two terms are used interchangeably. In this book, when we refer to a LUN, we refer to the unit of storage that is defined in a storage subsystem such as an IBM System Storage Enterprise Storage Server (ESS), IBM System Storage DS4000, DS6000, and DS8000 series Storage Server, or storage servers from other vendors.

Managed diskA managed disk (MDisk) is a SCSI disk presented by a RAID controller and managed by the SAN Volume Controller. The MDisk must not be configured to be visible to host systems on the SAN.

Managed disk groupThe managed disk group (MDG) is a collection of MDisks that jointly contain all the data for a specified set of VDisks.

Master consoleThe master console is the platform on which the software used to manage the SAN Volume Controller runs.

NodeA node is a name given to the individual servers in a SAN Volume Controller cluster on which the SAN Volume Controller software runs.

SAN Volume ControllerThe SAN Volume Controller is a SAN appliance designed for attachment to a variety of host computer systems, which carries out block level virtualization of disk storage.

Vir