Novell LINUX ENTERPRISE SERVER 10 SP2 - STORAGE ADMINISTRATION GUIDE... Instruction Manual

Novell®
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novdocx (en) 13 May 2009
AUTHORIZED DOCUMENTATION
SLES 10 SP2: Storage Administration Guide
SUSE ® Linux Enterprise Server
10 SP2
May 15, 2009
Storage Administration Guide

novdocx (en) 13 May 2009
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4SLES 10 SP2: Storage Administration Guide
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Contents 5
Contents
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About This Guide 9
1 Overview of EVMS 11
1.1 Benefits of EVMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.2 Plug-In Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.3 Supported File Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.4 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.5 Location of Device Nodes for EVMS Storage Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2 Using EVMS to Manage Devices 15
2.1 Configuring the System Device at Install to Use EVMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1.1 Before the Install . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1.2 During the Server Install . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.1.3 After the Server Install . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.2 Configuring an Existing System Device to Use EVMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.2.1 Disable the boot.lvm and boot.md Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.2.2 Enable the boot.evms Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.2.3 Edit the /etc/fstab File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.2.4 Edit the Boot Loader File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.2.5 Force the RAM Disk to Recognize the Root Partition . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2.6 Restart the Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.2.7 Verify that EVMS Manages the Boot, Swap, and Root Partitions . . . . . . . . . . . . . . . 26
2.3 Configuring LVM Devices to Use EVMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.4 Using EVMS with iSCSI Volumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.5 Using the ELILO Loader Files (IA-64) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.6 Starting EVMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.7 Starting the EVMS Management Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3 Using UUIDs to Mount Devices 31
3.1 Naming Devices with udev . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2 Understanding UUIDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2.1 Using UUIDs to Assemble or Activate File System Devices . . . . . . . . . . . . . . . . . . . 32
3.2.2 Finding the UUID for a File System Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.3 Using UUIDs in the Boot Loader and /etc/fstab File (x86) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.4 Using UUIDs in the Boot Loader and /etc/fstab File (IA64) . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.5 Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4 Managing EVMS Devices 35
4.1 Understanding Disk Segmentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.1.1 Segment Managers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.1.2 Disk Segments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.2 Initializing Disks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.2.1 Before You Begin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.2.2 Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.2.3 Adding a Segment Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.3 Removing the Segment Manager from a Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

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4.4 Creating Disk Segments (or Partitions) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.5 Configuring Mount Options for Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.6 What’s Next . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5 Managing Multipath I/O for Devices 43
5.1 Understanding Multipathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.1.1 What Is Multipathing? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.1.2 Benefits of Multipathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
5.2 Planning for Multipathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
5.2.1 Guidelines for Multipathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
5.2.2 Using Multipathed Devices Directly or in EVMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.2.3 Using LVM2 on Multipath Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.2.4 Using mdadm with Multipath Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.2.5 Partitioning Multipath Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.2.6 Supported Architectures for Multipath I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.2.7 Supported Storage Arrays for Multipathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.3 Multipath Management Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
5.3.1 Device Mapper Multipath Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
5.3.2 Multipath I/O Management Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.3.3 Using mdadm for Multipathed Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
5.3.4 The Linux multipath(8) Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
5.4 Configuring the System for Multipathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.4.1 Preparing SAN Devices for Multipathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.4.2 Partitioning Multipathed Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.4.3 Configuring the Server for Multipathing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.4.4 Adding multipathd to the Boot Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.4.5 Creating and Configuring the /etc/multipath.conf File . . . . . . . . . . . . . . . . . . . . . . . . 55
5.5 Enabling and Starting Multipath I/O Services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
5.6 Configuring Path Failover Policies and Priorities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
5.6.1 Configuring the Path Failover Policies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
5.6.2 Configuring Failover Priorities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5.6.3 Using a Script to Set Path Priorities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.6.4 Configuring ALUA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.6.5 Reporting Target Path Groups. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.7 Tuning the Failover for Specific Host Bus Adapters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.8 Configuring Multipath I/O for the Root Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.9 Configuring Multipath I/O for an Existing Software RAID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
5.10 Scanning for New Devices without Rebooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
5.11 Scanning for New Partitioned Devices without Rebooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5.12 Viewing Multipath I/O Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.13 Managing I/O in Error Situations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5.14 Resolving Stalled I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.15 Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.16 What’s Next . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
6 Managing Software RAIDs with EVMS 75
6.1 Understanding Software RAIDs on Linux. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
6.1.1 What Is a Software RAID?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
6.1.2 Overview of RAID Levels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6.1.3 Comparison of RAID Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.1.4 Comparison of Disk Fault Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.1.5 Configuration Options for RAIDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.1.6 Interoperability Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

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6.1.7 Guidelines for Component Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.1.8 RAID 5 Algorithms for Distributing Stripes and Parity . . . . . . . . . . . . . . . . . . . . . . . . 80
6.1.9 Multi-Disk Plug-In for EVMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6.1.10 Device Mapper Plug-In for EVMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6.2 Creating and Configuring a Software RAID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6.3 Expanding a RAID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.3.1 Adding Mirrors to a RAID 1 Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.3.2 Adding Segments to a RAID 4 or 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.4 Adding or Removing a Spare Disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.4.1 Do You Need a Spare Disk? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.4.2 Adding a Spare Disk When You Create the RAID. . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.4.3 Adding a Spare Disk to an Existing RAID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.4.4 Removing a Spare Disk from a RAID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.5 Managing Disk Failure and RAID Recovery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.5.1 Understanding the Disk Failure and RAID Recovery. . . . . . . . . . . . . . . . . . . . . . . . . 87
6.5.2 Identifying the Failed Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
6.5.3 Replacing a Failed Device with a Spare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.5.4 Removing the Failed Disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.6 Monitoring Status for a RAID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.6.1 Monitoring Status with EVMSGUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6.6.2 Monitoring Status with /proc/mdstat. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.6.3 Monitoring Status with mdadm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.6.4 Monitoring a Remirror or Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
6.6.5 Configuring mdadm to Send an E-Mail Alert for RAID Events. . . . . . . . . . . . . . . . . . 93
6.7 Deleting a Software RAID and Its Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7 Managing Software RAIDs 6 and 10 with mdadm 97
7.1 Creating a RAID 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
7.1.1 Understanding RAID 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
7.1.2 Creating a RAID 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
7.2 Creating Nested RAID 10 Devices with mdadm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
7.2.1 Understanding Nested RAID Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
7.2.2 Creating Nested RAID 10 (1+0) with mdadm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
7.2.3 Creating Nested RAID 10 (0+1) with mdadm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
7.3 Creating a Complex RAID 10 with mdadm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
7.3.1 Understanding the mdadm RAID10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
7.3.2 Creating a RAID10 with mdadm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
7.4 Creating a Degraded RAID Array. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
8 Resizing Software RAID Arrays with mdadm 107
8.1 Understanding the Resizing Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
8.1.1 Guidelines for Resizing a Software RAID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
8.1.2 Overview of Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
8.2 Increasing the Size of a Software RAID. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
8.2.1 Increasing the Size of Component Partitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
8.2.2 Increasing the Size of the RAID Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
8.2.3 Increasing the Size of the File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
8.3 Decreasing the Size of a Software RAID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
8.3.1 Decreasing the Size of the File System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
8.3.2 Decreasing the Size of Component Partitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
8.3.3 Decreasing the Size of the RAID Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

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9 Installing and Managing DRBD Services 117
9.1 Understanding DRBD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
9.2 Installing DRBD Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
9.3 Configuring the DRBD Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
9.4 Testing the DRBD Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
9.5 Troubleshooting DRBD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
9.5.1 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
9.5.2 Host Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
9.5.3 TCP Port 7788 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
9.5.4 The --do-what-i-say Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
9.6 Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
10 Troubleshooting Storage Issues 123
10.1 Is DM-MP Available for the Boot Partition? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10.2 Rescue System Cannot Find Devices That Are Managed by EVMS . . . . . . . . . . . . . . . . . . . 123
10.3 Volumes on EVMS Devices Do Not Appear After Reboot . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10.4 Volumes on EVMS Devices Do Not Appear When Using iSCSI . . . . . . . . . . . . . . . . . . . . . . 124
10.5 Device Nodes Are Not Automatically Re-Created on Restart . . . . . . . . . . . . . . . . . . . . . . . . 124
A Documentation Updates 125
A.1 May 15, 2009 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
A.1.1 Managing Multipath I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
A.2 November 24, 2008 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
A.2.1 Managing Multipath I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
A.2.2 Using UUIDs to Mount Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
A.3 June 10, 2008 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
A.3.1 Managing Multipath I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
A.4 March 20, 2008 (SLES 10 SP2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
A.4.1 Managing Multipath I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

About This Guide 9
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About This Guide
This guide provides information about how to manage storage devices on a SUSE®Linux
Enterprise Server 10 Support Pack 2 server with an emphasis on using the Enterprise Volume
Management System (EVMS) 2.5.5 or later to manage devices. Related storage administration
issues are also covered as noted below.
Chapter 1, “Overview of EVMS,” on page 11
Chapter 2, “Using EVMS to Manage Devices,” on page 15
Chapter 3, “Using UUIDs to Mount Devices,” on page 31
Chapter 4, “Managing EVMS Devices,” on page 35
Chapter 5, “Managing Multipath I/O for Devices,” on page 43
Chapter 6, “Managing Software RAIDs with EVMS,” on page 75
Chapter 7, “Managing Software RAIDs 6 and 10 with mdadm,” on page 97
Chapter 8, “Resizing Software RAID Arrays with mdadm,” on page 107
Chapter 9, “Installing and Managing DRBD Services,” on page 117
Chapter 10, “Troubleshooting Storage Issues,” on page 123
Audience
This guide is intended for system administrators.
Feedback
We want to hear your comments and suggestions about this manual and the other documentation
included with this product. Please use the User Comments feature at the bottom of each page of the
online documentation, or go to www.novell.com/documentation/feedback.html and enter your
comments there.
Documentation Updates
For the most recent version of the SUSE Linux Enterprise Server 10 Storage Administration Guide
for EVMS, visit the Novell Documentation Web site for SUSE Linux Enterprise Server 10 (http://
www.novell.com/documentation/sles10).
Additional Documentation
For information about managing storage with the Linux Volume Manager (LVM), see the SUSE
Linux Enterprise Server 10 Installation and Administration Guide (http://www.novell.com/
documentation/sles10).
For information about iSNS (Internet Storage Name Service), see “iSNS” (http://www.novell.com/
documentation/sles10/sles_admin/index.html?page=/documentation/sles10/sles_admin/data/
cha_isns.html) in the SUSE Linux Enterprise Server 10 Installation and Administration Guide (http:/
/www.novell.com/documentation/sles10).

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Documentation Conventions
In Novell documentation, a greater-than symbol (>) is used to separate actions within a step and
items in a cross-reference path.
A trademark symbol (®, TM, etc.) denotes a Novell trademark. An asterisk (*) denotes a third-party
trademark.

Overview of EVMS
1
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1
Overview of EVMS
The Enterprise Volume Management System (EVMS) 2.5.5 management tool for Linux* is an
extensible storage management tool that integrates all aspects of volume management, such as disk
partitioning, the Logical Volume Manager (LVM), the Multiple-Disk (MD) manager for software
RAIDs, the Device Mapper (DM) for multipath I/O configuration, and file system operations.
Section 1.1, “Benefits of EVMS,” on page 11
Section 1.2, “Plug-In Layers,” on page 11
Section 1.3, “Supported File Systems,” on page 12
Section 1.4, “Terminology,” on page 12
Section 1.5, “Location of Device Nodes for EVMS Storage Objects,” on page 13
1.1 Benefits of EVMS
EVMS provides the following benefits:
An open source volume manager
A plug-in framework for flexible extensibility and customization
Plug-ins to extend functionality for new or evolving storage managers
Support for foreign partition formats
Cluster-aware
1.2 Plug-In Layers
EVMS abstracts the storage objects in functional layers to make storage management more user-
friendly. The following table describes the current EVMS plug-in layers for managing storage
devices and file systems:
Table 1-1 EVMS Plug-In Layers
Storage Managers Description Plug-Ins
Device Manages the physical and logical
devices
Device Mapper (DM)
Segment Manages the partitioning of
physical and logical devices into
smaller segments of free space.
Segment managers can be
stacked. For example, a cluster
segment can contain other
storage objects or volumes.
Uses Device Mapper (DM)
Segment managers include DOS,
GPT, System/390* (S/390),
Cluster, BSD, Mac, and BBR
For more information, see
Section 4.1, “Understanding Disk
Segmentation,” on page 35.

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1.3 Supported File Systems
EVMS supports the following Linux file systems:
EXT3
ReiserFS
XFS
OCFS2
JFS
EXT2
Swap
NTFS (read only)
FAT (read only)
For more information about file systems supported in SUSE®Linux Enterprise Server 10, see the
SUSE Linux Enterprise Server 10 Installation and Administration Guide. (http://www.novell.com/
documentation/sles10).
The File System Primer (http://wiki.novell.com/index.php/File_System_Primer) describes the
variety of file systems available on Linux and which ones are the best to use for which workloads
and data.
1.4 Terminology
EVMS uses the following terminology in the EVMS user interface:
Table 1-2 EVMS Terms
Regions Manages the combination of
multiple storage objects
LVM/LVM2 for containers and
region, MD for RAIDs, and DM for
multipath I/O
EVMS Features Manages EVMS features Drive linking (linear
concatenation), Bad Block
Relocation (BBR), and Snapshot
File System Interface Modules
(FSIM)
Manages the interface between
the file system managers and the
segment managers
For information, see Section 1.3,
“Supported File Systems,” on
page 12.
Cluster Manager Interface
Modules
Manages the interface between
the cluster manager and the file
systems and devices
HeartBeat 2
Term Description
Sector The lowest level that can be addressed on a block device.
Disk A physical disk or a logical device.
Storage Managers Description Plug-Ins

Overview of EVMS 13
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1.5 Location of Device Nodes for EVMS Storage
Objects
EVMS creates a unified namespace for the logical volumes on your system in the /dev/evms
directory. It detects the storage objects actually present on a system, and creates an appropriate
device node for each one, such as those shown in the following table.
Segment An ordered set of physically contiguous sectors on a single device. It is similar
to traditional disk partitions.
Region An ordered set of logically contiguous sectors that might or might not be
physically contiguous. The underlying mapping can be to logical disks, disk
segments, or other storage regions.
Feature
(Feature Object, EVMS
Feature, EVMS Object)
A logically contiguous address space created from one or more disks,
segments, regions, or other feature objects through the use of an EVMS
feature.
Storage Object Any storage structure in EVMS that is capable of being a block device. Disks,
segments, regions, and feature objects are all storage objects.
Container
(Storage Container)
A collection of devices that is managed as a single pool of storage.
Private Storage Container: A storage container that is exclusively owned and
accessed by only one server.
Cluster Storage Container: A storage container managed by the Cluster
Resource Manager. It is accessible to all nodes of a cluster. An administrator
can configure the storage objects in the cluster container from any node in the
cluster. Cluster containers can be private, shared, or deported.
Private: The cluster container is exclusively owned and accessed by only
one particular node of a cluster at any given time. The ownership can be
reassigned by failover policies or the administrator.
Shared: The cluster container is concurrently owned and accessed by all
nodes of a cluster. Shared containers are preferred for distributed
databases, clustered file systems, and cluster-aware applications that can
coordinate safe access to shared volumes.
Deported: The cluster container is not owned or accessed by any node of
the cluster.
Volume
(Logical Volume)
A mountable storage object. Logical volumes can be EVMS volumes or
compatibility volumes.
EVMS Volume: Volumes that contain EVMS metadata and support all
EVMS features. Device nodes for EVMS volumes are stored in the /dev/
evms
directory. For example: /dev/evms/my_volume
Compatibility Volume: Volumes that are backward-compatible to other
volume managers. They do not contain EVMS metadata and cannot
support EVMS features.
Term Description

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Table 1-3 Device Node Location
Storage Object Standard Location the Device Node EVMS Location of the Device Node
A disk segment of disk /dev/sda5 /dev/evms/sda5
A software RAID device /dev/md1 /dev/evms/md/md1
An LVM volume /dev/lvm_group/lvm_volume /dev/evms/lvm/lvm_group/
lvm_volume

Using EVMS to Manage Devices
2
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2
Using EVMS to Manage Devices
This section describes how to configure EVMS as the volume manager of your devices.
Section 2.1, “Configuring the System Device at Install to Use EVMS,” on page 15
Section 2.2, “Configuring an Existing System Device to Use EVMS,” on page 22
Section 2.3, “Configuring LVM Devices to Use EVMS,” on page 27
Section 2.4, “Using EVMS with iSCSI Volumes,” on page 27
Section 2.5, “Using the ELILO Loader Files (IA-64),” on page 28
Section 2.6, “Starting EVMS,” on page 28
Section 2.7, “Starting the EVMS Management Tools,” on page 28
2.1 Configuring the System Device at Install to
Use EVMS
This section describes how to configure the system device during the Linux install to use EVMS as
the volume manager instead of the current default of Linux Volume Manager (LVM).
Section 2.1.1, “Before the Install,” on page 15
Section 2.1.2, “During the Server Install,” on page 17
Section 2.1.3, “After the Server Install,” on page 20
2.1.1 Before the Install
“System Device” on page 15
“Device Size Limits” on page 16
“Data Loss Considerations for the System Device” on page 16
“Storage Deployment Considerations for the System Device” on page 16
System Device
For the purposes of this install documentation, a system device is any device that contains the Linux
/boot , swap , or root ( / ) partitions for your Linux computer.
The install instructions assume the following:
All three system partitions are on the same physical disk.
If you use different disks for any of the system partitions, make sure to modify the install
instructions for your deployment scenario so that all of the system partitions are managed by
EVMS.
You must configure the boot partition within the BIOS-addressable space (such as 2 GB for x86
or 8 GB for x86-64) of the first disk recognized by the system.
If this restriction is not required for your hardware, you can modify the location of the
/boot
partition as desired.

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Your system uses the Grub or LILO boot loaders.
If you have an IA64 system, you must modify these install instructions to use the ELILO boot
loader (
/boot/efi/elilo.conf ) instead.
WARNING: Whenever you manually alter the kernel or initrd on your system, make sure to
run
/sbin/elilo before shutting down the computer. If you leave out this step, your system
might not be bootable.
Device Size Limits
Version 2.3 and later of
mdadm supports component devices up to 4 TB in size each. Earlier versions
support component devices up to 2 TB in size.
IMPORTANT: If you have a local disk, external disk arrays, or SAN devices that are larger than the
supported device size, use a third-party disk partitioner to carve the devices into smaller logical
devices.
You can combine up to 28 component devices to create the RAID array. The
md RAID device you
create can be up to the maximum device size supported by the file system you plan to use. For
information about file system limits for SUSE®Linux Enterprise Server 10, see “Large File System
Support” in the SUSE Linux Enterprise Server 10 Installation and Administration Guide. (http://
www.novell.com/documentation/sles10).
Data Loss Considerations for the System Device
This install requires that you delete the default partitioning settings created by the install, and create
new partitions to use EVMS instead. This destroys all data on the disk.
WARNING: To avoid data loss, it is best to use the EVMS install option only on a new device.
If you have data volumes on the system device, take one or more of the following precautionary
measures:
Move the data volumes from the system device to another device.
If you cannot move the volumes, make a backup copy of the data, so you can restore the data
volumes later from a backup copy.
Storage Deployment Considerations for the System Device
By default, the YaST install for SUSE Linux Enterprise Server uses the Linux Volume Manager to
manage the system device. The install procedures in this section describe how to install SUSE Linux
Enterprise Server with EVMS as the volume manager of the system device. The instructions assume
the following:
You want to use EVMS to manage the system device.
Only the system device is to be configured during the install.
Other devices on the system are not configured during the install, or are attached to the server
later. These additional devices are configured only after the system is operating and performing
as expected.

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2.1.2 During the Server Install
To install Linux with EVMS as the volume manager for your boot and system partitions, you must
modify the Partitioning configuration in the Installation Settings.
WARNING: The following procedure destroys all data on the system device.
1Begin the install, according to the instructions provided in Deployment (http://
www.novell.com/documentation/sles10/sles_admin/data/part_setup.html) in the SUSE Linux
Enterprise 10 Installation and Administration Guide (http://www.novell.com/documentation/
sles10/sles_admin/data/bookinfo_book_sles_admin.html).
2When the installation reaches the Installations Settings screen, delete the proposed LVM-based
partioning solution. This deletes the proposed partitions and the partition table on the system
device so that the device can be marked to use EVMS as the volume manager instead of LVM.
2a In the list of Installation Settings, select Partitioning.
2b In the Partitioning menu, select Create Custom Partition Setup, then click Next.
2c Select Custom Partition - for Experts, then click Next to open the Expert Partitioner
dialog box.
2d Select Expert > Delete Partition Table and Disk Label, then click Yes twice to continue
through the Warning advisories.
This deletes the recommended partitions and the partition table on the system disk.
3Create a primary partition on the system disk to use as the boot partition:
3a Click Create.
3b From the list of devices, select the device you want to use for the boot partition, such as
/
dev/hda
, then click OK.
If you have a single system disk, only one device is available, and you are not prompted to
choose the device.
3c Select Primary Partition, then click OK.
3d Select Format, then select the native Linux file system you want to use, such as Ext3.
IMPORTANT: In a paravirtualized environment, use Ext2 as the file system for the boot
device.
3e In Size (End Value) field, specify 200 MB or larger.
For example, to set the size at 300 MB, type
300M .
3f Set the mount point to /boot.
3g Click OK.
The partition appears as a logical device in the devices list, such as
/dev/hda1 .
4Create a second primary partition on the system disk to use for both the swap and system
volumes:
4a Click Create.
4b From the list of devices, select the device you want to use for the second primary partition,
such as
/dev/hda , then click OK.
If you have a single system disk, only one device is available and you are not prompted to
choose the device.

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4c Select Primary Partition, then click OK.
4d Select Do Not Format, then select Linux LVM (0x8E) from the list of file system IDs.
4e In Size (End Value field), set the cylinder End value to 5 GB or larger, depending on the
combined partition size you need to contain your system and swap volumes.
IMPORTANT: Do not make the system partition larger than necessary. The remaining
space on the system disk can be used to create NSS volumes or native Linux volumes that
are managed by EVMS.
To determing how much space to use, consider the following recommendations:
For your system volume, allow 2 GB (minimum) to 10 GB (recommended),
depending on the OES services that you intend to install.
If you intend to create additional NSS volumes on the same physical disk, you must
leave unpartitioned space available.
Set aside 128 MB or larger for the swap volume.
Swap management is different for Linux kernel 2.4.10 and later. How much swap to
add depends on the RAM size, the tasks that are planned for the system, and whether
you want to make more virtual memory available than the RAM provides.
Some swap (at least 128 MB) is good to have to minimize the risk of losing data
when active processes run out of RAM space. Swap is not required for systems with
more than 1 GB of RAM. You must have at least 1 GB of virtual memory (RAM plus
swap) during the install, but if the swap is more than 2 GB, you might not be able to
install on some machines.
The total size should be the size you need for your system volume plus the size you
need for your swap volume.
For example, if you have a 20 GB hard drive with 2 GB of RAM and plan to install all of
the OES services on the system volume, your system partition should be at least 11 GB.
The remaining 9 GB should remain as free unpartitioned space that can be used for NSS
volumes or other Linux partitions that you might want to create later.
4f Click OK.
The partition appears as a logical device in the devices list, such as
/dev/hda2 .
5Modify the volume management type from LVM to EVMS for the second primary partition
you created in Step 4:
5a At the bottom of the page, click EVMS.
Available partitions for EVMS appear as devices under
/dev/evms , such as /dev/evms/
hda2
.
5b In the EVMS Configurator, select the LVM partition created in Step 4, then click Create
Container.
5c In the Create EVMS Container dialog box, select the partition, specify the container name
(such as
system ), then click Add Volume to create the lvm/system container, where
system is the container name.
5d Click OK.
The EVMS Configurator displays the
lvm/system container you just created, its size, and
free space.

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6Create the swap volume in the lvm/system container:
6a Select
lvm/system , then click Add.
6b In the Create Logical Volume dialog box, select Format, then select Swap from the File
System drop-down menu.
6c Specify
swap as the volume name.
6d Specify 1 GB (recommended) for the swap volume.
The swap size should be 128 MB or larger, with a recommended size of 1 GB. For an
explanation of this recommendation, see Step 4e.
6e Specify the mount point as swap.
6f Click OK.
7Create the system volume in the
lvm/system container:
7a Select
lvm/system , then click Add.
7b In the Create Logical Volume dialog box, select Format, then select the file system to use
from the File System drop-down menu, such as Reiser or Ext3.
7c In the Volume Name field, specify a volume name, such as
sys_lx .
7d In the Size field, click Max to set the size of the system volume as the remaining space
available in the
lvm/system partition.
7e Specify the mount point as
/ (root volume).
7f Click OK.
8Click Next to return to the list of devices.
Below is an example of the physical and logical devices that should be configured on your
system. Your setup depends on the number of devices in the server and the sizes you choose for
your partitions.
9Click Next to return to the Installation Settings page.
You can dismiss the message warning that you should not mix EVMS and non-EVMS
partitions on the same device.
10 Continue with the SUSE Linux Enterprise Server installation.
Device Size F Type Mount Start End Used By
/dev/hda 149.0 GB 6Y160p0 0 19456
/dev/hda1 305.9 MB F Linux Native
(Reiser)
/boot 038
/dev/hda2 20.0 GB Linux LVM 39 2649 EVMS
lvm/
system
/dev/hdb
111.8 GB SP1203N 0 14595
/dev/evms/lvm/system/
sys_lx
10.0 GB F EVMS / --
/dev/evms/lvm/system/
swap
1.0 GB F EVMS swap --

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IMPORTANT: After the install is complete, make sure to perform the mandatory post-install
configuration of the related system settings to ensure that the system device functions properly
under EVMS. Otherwise, the system fails to boot properly.
For information, see “After the Server Install” on page 20.
2.1.3 After the Server Install
After the SUSE Linux Enterprise Server 10 install is complete, you must perform the following
tasks to ensure that the system device functions properly under EVMS:
“Edit the /etc/fstab File” on page 20
“Make a New initrd” on page 21
“Disable the boot.lvm and boot.md Services” on page 21
“Enable the boot.evms Service” on page 21
“Restart the Server” on page 22
“Verify the System Services” on page 22
Edit the /etc/fstab File
When you boot the system, the kernel reads the
/etc/fstab file to identify which file systems
should be mounted and then mounts them. This file contains a table of file system information about
the root (
/ ), /boot , and swap partitions plus other partitions and file systems you want to mount.
The /boot partition is separate from the EVMS container where you placed the root ( / ) and swap
partitions and is not managed by EVMS at this time. However, in the following steps, you disable
boot.lvm and boot.md , then enable boot.evms . In effect, this forces EVMS to scan all the
partitions at boot time, including the
/boot partition, and it activates /boot under the /dev/evms
directory. Therefore, this makes
/boot a partition that is discovered by EVMS at startup, and
requires that the device be listed under
/dev/evms in the fstab file so it can be found when booting
with
boot.evms . You must edit the /etc/fstab file to modify the location of the /boot partition
so it is under the
/dev/evms directory.
In fstab , the entry for the boot device might present the boot device by the device node name (such
as
/dev/sda1 ) or by the UUID pathname (such as /dev/disk/by-id/scsi-
SServeRA_Drive_1_600BC00000-part1
). In ether case, that name for the boot device must be
changed to include
evms in the path, such as /dev/evms/sda1 .
The procedure in this section shows how to change /dev/sda1 to /dev/evms/sda1 . Replace sda1
with the device name of the device you used for your
/boot partition.
IMPORTANT: When working in the /etc/fstab file, do not leave any stray characters or spaces
in the file. This is a configuration file, and it is highly sensitive to such mistakes.
To modify the path of the boot device in the
/etc/fstab file, complete the following procedure:
1Open the
/etc/fstab file in a text editor.
2Locate the line that contains the
/boot partition.
For example, if your
/boot partition uses device sda1 and the Reiser file system, look for a
line similar to this: