3.1.2 VERITAS Volume Manager Administration Considerations

For Sun Cluster to maintain the VxVM namespace, you must register any VxVM disk group or volume changes as Sun Cluster disk device group configuration changes. Registering these changes ensures that the namespace on all cluster nodes is updated. Examples of configuration changes that impact the namespace include adding, removing, or renaming a volume; and changing the volume permissions, owner, or group ID.

Never import or deport VxVM disk groups using VxVM commands once the disk group has been registered with the cluster as a Sun Cluster disk device group. The Sun Cluster software will handle all cases where disk groups need to be imported or deported.

Each VxVM disk group must have a cluster-wide unique minor number. By default, when a disk group is created, VxVM chooses a random number that is a multiple of 1000 as that disk group's base minor number. For most configurations with only a small number of disk groups, this is sufficient to guarantee uniqueness. However, it is possible that the minor number for a newly-created disk group will conflict with the minor number of a pre-existing disk group imported on a different cluster node. In this case, attempting to register the Sun Cluster disk device group will fail. To fix this problem, the new disk group should be given a new minor number that is a unique value and then registered as a Sun Cluster disk device group.

If you are setting up a mirrored volume, Dirty Region Logging (DRL) can be used to decrease volume recovery time in the event of a system crash. Use of DRL is strongly recommended, although it could decrease I/O throughput.