Using Serviceguard Extension for RAC, 4th Edition, February 2007

Maintenance and Troubleshooting
Managing the Shared Storage
Chapter 4192
Managing the Shared Storage
Single Node Online volume Re-Configuration (SNOR)
The SLVM Single Node Online volume Re-configuration (SNOR) feature
provides a method for changing the configuration for an active shared
VG in a SGeRAC cluster.
SLVM SNOR allows the reconfiguration of a shared volume group and of
logical and physical volumes in the VG. This is done while keeping the
VG active on a single node in exclusive mode. After the reconfiguration,
the VG can be reactivated in shared mode and later can be activated on
other nodes.
In addition, as the VG is activated on a single node, in exclusive mode,
the application can be up and running. The volume group changes need
to be performed on the node when the vgchange command is executed.
The command line option to the vgchange command (vgchange -a <e
or s> -x) allows activation mode switches between “shared” and
“exclusive” on a shared VG active in a single node.
Use the following procedures to set up an on-line re-configuration:
1. Identify the shared volume group on which a configuration change is
required, for example vg_shared.
2. Identify one node, for example node1, of the cluster that is running
an application, such as RAC using the shared volume group. The
applications using the volume group, vg_shared, on this node will
remain unaffected during the procedure. The cluster application
needs to be scaled down to a single cluster node, using the volume
group, vg_shared.
3. On all other nodes of the cluster, except node1, deactivate the volume
group using the -n option to vgchange(1M). For example,
# vgchange -a n vg_shared
Ensure the volume group, vg_shared, is now active only on a single
cluster node, node1.
4. Change the activation mode to exclusive on the node1 where the
volume group is active, use the vgchange(1M) command option. For
example,