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. Changing the volume permissions, owner, or group ID also impacts the namespace.

  ---

  Note –

  Never import or deport VxVM disk groups by using VxVM commands once the disk group has been registered with the cluster as a Sun Cluster disk device group. The Sun Cluster software handles all cases where disk groups need to be imported or be 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, the minor number is sufficient to guarantee uniqueness. The minor number for a newly-created disk group might conflict with the minor number of a pre-existing disk group that was imported on a different node. In this case, attempting to register the Sun Cluster disk device group fails. 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 after a node failure. Use of DRL is strongly recommended, although use of DRL could decrease I/O throughput.

• VxVM does not support the chmod command. To change global device permissions in VxVM, consult the VxVM administrator's guide.

• Sun Cluster 3.1 software does not support VxVM Dynamic Multipathing (DMP) to manage multiple paths from the same node.

• If you use VxVM to set up shared disk groups for Oracle Parallel Server/Real Application Clusters, use the cluster functionality of VxVM as described in the VERITAS Volume Manager Administrator's Reference Guide. There are differences between creating shared disk groups for Oracle Parallel Server/Real Application Clusters and creating other disk groups. You must import the Oracle Parallel Server/Real Application Clusters shared disk groups by using vxdg -s. You do not register the Oracle Parallel Server/Real Application Clusters shared disk groups with the cluster framework. To create other VxVM disk groups, see How to Create a New Disk Group When Initializing Disks (VERITAS Volume Manager).