LVM Volume Group Quiesce/Resume

The LVM Quiesce/Resume feature is supported on Serviceguard clusters
A volume group activated in shared mode can be quiesced from any node in the cluster
and resumed from any node. Invoking the command to quiesce the volume group on
any node causes the volume group to be quiesced on all the nodes of the cluster.
Likewise resuming the volume group from any node in the cluster will resume it on all
the nodes.
A quiesced volume group activated in exclusive mode behaves like a quiesced
standalone volume group, with these additional features:
 While the volume group is quiesced, the volume group may not be transitioned
from exclusive mode to shared mode.
A quiesced shared volume group behaves like a quiesced standalone volume
group, with these additional features:
 The Volume Group Quiesce/Resume feature is resilient to cluster node
reconfiguration. Once a shared volume group is quiesced, if a node leaves the
cluster, the volume group remains quiesced on the remaining nodes.
 Once a shared volume group is quiesced, activating the volume group on any
additional cluster nodes will fail until the volume group is resumed.
 While the volume group is quiesced, the volume group cannot be transitioned
from shared mode to exclusive mode.
 Quiescing a volume group containing the Serviceguard Cluster Lock disk is
disallowed.
 All the nodes of the cluster must have the Volume Group Quiesce/Resume
feature installed before using it. Nodes that do not provide the feature, cannot
be quiesced and may continue to modify the volume group even when the
volume group appears quiesced from other nodes that do provide the feature. If
the volume group cluster server does not provide the feature, attempting to
quiesce the volume group from a cluster client can cause the vgchange
command to stall until the volume group is deactivated on all the nodes that do
not provide the feature.
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