SLVM Online Volume Reconfiguration (September 2009)

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SLVM Online Volume Reconfiguration

Abstract.............................................................................................................................................. 2

Multi Node Online Reconfiguration........................................................................................................ 2

Prerequisites .................................................................................................................................... 2

LVM Command Changes .................................................................................................................. 2

lvmerge and lvsplit Behavior Change ................................................................................................. 3

On which node do you issue the LVM commands?............................................................................... 3

Volume naming................................................................................................................................3

Which nodes in an HP Serviceguard cluster receive the changes? ......................................................... 3

/etc/lvmtab and /etc/lvmtab_p ........................................................................................................ 4

Activating a shared volume group...................................................................................................... 4

Alternate PV links ............................................................................................................................. 4

Physical volume groups and the lvmpvg file......................................................................................... 5

Online disk replacement ................................................................................................................... 5

Troubleshooting ............................................................................................................................... 5

Example 1................................................................................................................................... 5

Example 2................................................................................................................................... 5

SNOR ................................................................................................................................................ 6

Application and availability considerations ......................................................................................... 6

Commands...................................................................................................................................... 7

vmchange(1M)............................................................................................................................. 7

Procedures ...................................................................................................................................... 7

Making a configuration change in an active shared volume group..................................................... 7

Determining whether SLVM SNOR is available on the system ................................................................ 8

SLVM SNOR Messages .................................................................................................................... 9

vgchange(1M) ............................................................................................................................. 9

Required software and patch list ...................................................................................................... 10

Summary of content (10 pages)

PAGE 1
SLVM Online Volume Reconfiguration Abstract.............................................................................................................................................. 2 Multi Node Online Reconfiguration........................................................................................................ 2 Prerequisites .................................................................................................................................... 2 LVM Command Changes ..............
PAGE 2
Abstract SLVM (Shared Logical Volume Manager) is a mechanism that permits multiple systems in an HP Serviceguard cluster to share (read/write) disk resources in the form of volume groups. Starting with the HP-UX 11i v3 September 2009 release, you can change the configuration of a shared volume group while it stays activated on all the nodes. There is no need to deactivate the volume group on some nodes. This method is called Multi Node Online Reconfiguration (MORE).
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Commands that were already working on online shared volume groups continue to work as before. For example, the display commands, lvsync. The following commands are supported on a shared volume group Version 2.1 or higher. Before MORE (introduced in the HP-UX 11i v3 September 2009 release), these commands fail on a shared volume group.
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• When lvcreate, lvmerge , lvremove, or lvsplit is used, the logical volume device special files are automatically added or removed only on the nodes sharing the volume group. /etc/lvmtab and /etc/lvmtab_p The /etc/lvmtab file is not changed during online configuration of shared volume groups because /etc/lvmtab only applies to Version 1.0 volume groups. Online configuration of shared volume groups only applies to Version 2.1 volume groups.
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Physical volume groups and the lvmpvg file The physical volume groups work exactly the same way regardless of the activation mode of the volume group. In particular, you can use physical volume groups for configuration operations (lvextend) on shared volume groups. The /etc/lvmpvg file is not distributed across nodes automatically. The vgextend command acting on a shared volume group updates only the local /etc/lvmpvg file. This is identical to a standalone activation.
PAGE 6
On node2: # lvcreate -M y -m 1 -l 10 vg_bigmir lvcreate: The logical volume "/dev/vg_bigmir/lvol1" could not be created as a special file in the file-system: File exists In /var/adm/syslog/syslog.log: LVM: VG 128 0x005000: the distributed configuration failed 13 0 0 204. LVM: node node4.corp.
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Commands vmchange(1M) The vgchange –x option enables you to change the activation mode of a shared volume group. Changing the mode to exclusive from shared vgchange –a e -x vg_name The vgchange command provides an –x option that must be used together with the–a e option to change the activation mode of a shared volume group to exclusive mode. Upon success, the volume group is in the same state as if it had been activated in exclusive mode from inactive.
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Warning: If you run lvsplit on the logical volumes of a volume group in exclusive mode, changing the mode to shared results in discarding the bit map used for the subsequent fast lvmerge operation. In the absence of the bit map, an lvmerge operation causes the entire logical volume to be resynchronized (see lvsplit(1M) and lvmerge(1M)). 6. Export the changes to other cluster nodes if required.
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SLVM SNOR Messages vgchange(1M) • Usage: vgchange {-a Availability -q Quorum [-l] [-p] [-s] [VolumeGroupName... ]} {[-S shareable] -c cluster VolumeGroupName} {[-P parallel_nomwc_resync_count]} "x": Illegal option The –x option to vgchange was used on a system that does not have the SNOR LVM Commands patch. Install the appropriate LVM command patch (see Required software and patch list). • Activation of volume group "/dev/vg_shared" denied by another node in the cluster.
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Required software and patch list • For HP-UX 11i Version 1: LVM Patches PHKL_33390 and PHCO_33310 (or superseding patches) HP Serviceguard patch PHSS_33834 on HP Serviceguard 11.16 • For HP-UX 11i Version 2: LVM Patches PHKL_33312 and PHCO_33309 (or superseding patches) HP Serviceguard 11.17 release or HP Serviceguard patch PHSS_33835 on HP Serviceguard 11.16 © 2009 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.