SLVM Online Volume Reconfiguration (September 2009)

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.
If the configuration change required the creation or deletion of a new logical or physical volume
(any of the following commands were used: lvcreate(1M), lvreduce(1M), vgextend(1M),
vgreduce(1M), lvsplit(1M), lvmerge(1M)), the following sequence of steps is required.
Warning: If you used one of the preceding commands to change the configuration of the volume
group, and the mapfile, reflecting the change of configuration, is not imported on all the other
nodes, unexpected errors might occur. For example, errors are reported if:
– – A vgchange tries to reattach PVs that were removed using vgreduce.
– – A logical volume that was reduced with lvreduce is opened.
a) From node1, export the mapfile for vg_shared as follows:
vgexport -s -p -m /tmp/vg_shared.map vg_shared
b) Copy the /tmp/vg_shared mapfile to all the other nodes of the cluster.
c) On the other cluster nodes, export vg_shared and re-import it using the new map file.
ls -l /dev/vg_shared/group
crw-rw-rw- 1 root sys 64 0x050000 Nov 16 15:27 /dev/vg_shared/group
Note the minor number (0x050000 in the previous output)
vgexport vg_shared
mkdir /dev/vg_shared
mknod /dev/vg_shared/group c 64 0x050000
vgimport -m /tmp/vg_shared.map -s vg_shared
Note: The vgimport(1M) and vgexport(1M) sequence does not preserve the order of physical
volumes in the /etc/lvmtab file. If the ordering is significant due to the presence of active-
passive devices, or if the volume group was configured to maximize throughput by ordering the
paths accordingly, the ordering must be repeated. In this case, it might be better to use vgexport
and vgimport with the –f flag instead, and manually edit the file if device paths differ.
7. Change the activation mode back to shared in all the cluster nodes.
On node1, change the mode back to shared as follows:
vgchange -a s -x vg_shared
On the other cluster nodes, activate vg_shared in shared mode as follows:
vgchange -a s vg_shared
8. HP recommends using vgcfgbackup on all nodes to backup the changes made to the volume
group as follows:
vgcfgbackup vg_shared
Determining whether SLVM SNOR is available on the system
SLVM SNOR is available in patch form for HP-UX 11i v1 and v2 and as a standard feature in HP-UX
11i v3 releases. You must install patches for LVM commands and kernel components, and the
supported HP Serviceguard version on the system to enable the feature. It is not available if patches
for any of the three components are missing on the system. For a list of patches and kernel
components, see Required software and patch list.