HP-UX System Administrator's Guide: Logical Volume Management (762803-001, March 2014)

• For volume group Version 1.0 or 2.0, lvchange, lvcreate, lvextend, lvmerge, lvmove,
lvreduce, lvremove, lvsplit, vgextend, vgmodify, vgmove, and vgreduce cannot
be used in shared mode.
• The pvmove command cannot be used in shared mode for volume group Version 1.0.
• For pvchange, only the -a option (for attaching or detaching a path to the specified physical
volume) is allowed in shared mode. All other pvchange options are not supported in shared
mode.
To replace disks that are part of a volume group shared by a Serviceguard cluster, the physical
volume must be detached and attached (using pvchange) independently on each of the
systems in the cluster.
• The lvlnboot and lvrmbootcommands cannot be used in shared mode.
Volume group Version 2.2 and higher with snapshot logical volumes configured cannot be activated
in shared mode. Also, snapshots cannot be created off logical volumes belonging to shared volume
groups.
Synchronization of mirrored volume groups will be slower on shared volume groups.
Beginning with the September 2009 Update, LVM provides new options in LVM commands to let
system administrators reconfigure shared volume groups, logical volumes, and physical volumes
on multiple nodes in a cluster, while user applications and data reads/writes remain available
and active. lvmpud is the daemon that handles LVM online shared volume group reconfiguration.
The online reconfiguration of shared volume groups is only available on volume groups version
2.1 and higher. See the SLVM Online Reconfiguration white paper for details.
For Version 1.0 and 2.0 volume groups, you can use the vgchange -x option (the SLVM SNOR
feature) to change the configuration of a shared volume group, while keeping it active only on a
single node. Using this procedure, applications on at least one node remain available during the
volume group reconfiguration.
The shared LVM features, options, and restrictions are fully covered in the LVM command manpages.
See “LVM Command Summary” (page 165) for supported LVM commands. Each LVM command
has a manpage that is installed with the LVM product.
22 Introduction