SLVM Online Volume Reconfiguration (September 2009)

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.
The operation fails if the volume group is activated on any other node than the local node or if current
operations on the volume group do not allow an activation change. For example, loss of runtime
quorum (more than 50% of the last active set of physical volumes lost).
Changing the mode to shared from exclusive
vgchange –a s –x vg_name
The vgchange command provides an –x option that must be used together with the–a s option to
change the activation mode of an active volume group from exclusive to shared mode. Upon success,
the volume group is in the same state as if it had been activated in shared mode from inactive.
The operation fails if the volume group is currently inactive or activated in shared mode on the local
node, or if current operations on the volume group do not allow an activation change. For example,
loss of runtime quorum.
Procedures
Making a configuration change in an active shared volume group
1. Identify the shared volume group on which a configuration change is required. For example,
vg_shared.
2. Identify one node of the cluster that is running an application (for example, SGeRAC) using the
shared volume group. Call it node1. The applications using the vg_shared volume group on this
node remain unaffected during the procedure. You must scale the SGeRAC cluster application
down to the single cluster node, node1.
3. Deactivate the volume group on all other nodes of the cluster, except node1, using the –n option
to the vgchange command.
vgchange -a n vg_shared
Ensure the vg_shared volume group is now active only on a single cluster node, node1 by using
the vgdisplay command on all cluster nodes. The Status shows available on a single node
only.
4. Change the activation mode to exclusive on node1.
vgchange -a e -x vg_shared
Note: Ensure that none of the mirrored logical volumes in this volume group have Consistency
Recovery set to MWC (see lvdisplay(1M)). Changing the activation mode back to shared is not
allowed in that case, since Mirror Write Cache consistency recovery (MWC) is not valid in volume
groups activated in shared mode.
5. Make the desired configuration change on the volume group.
For example, on node1, run the required command to change the configuration as follows:
lvextend -m 2 /dev/vg_shared/lvol1