Consider the following points when you plan VERITAS Volume Manager (VxVM) configurations.
Enclosure-Based Naming – If you use Enclosure-Based Naming of devices, ensure that you use consistent device names on all cluster nodes that share the same storage. VxVM does not coordinate these names, so the administrator must ensure that VxVM assigns the same names to the same devices from different nodes. Failure to assign consistent names does not interfere with correct cluster behavior. However, inconsistent names greatly complicate cluster administration and greatly increase the possibility of configuration errors, potentially leading to loss of data.
Root disk group – As of VxVM 4.0, the creation of a root disk group is optional.
A root disk group can be created on the following disks:
The root disk, which must be encapsulated
One or more local nonroot disks, which you can encapsulate or initialize
A combination of root and local nonroot disks
The root disk group must be local to the node.
Simple root disk groups – Simple root disk groups (rootdg created on a single slice of the root disk) are not supported as disk types with VxVM on Sun Cluster software. This is a general VxVM software restriction.
Encapsulation – Disks to be encapsulated must have two disk-slice table entries free.
Number of volumes – Estimate the maximum number of volumes any given disk device group can use at the time the disk device group is created.
If the number of volumes is less than 1000, you can use default minor numbering.
If the number of volumes is 1000 or greater, you must carefully plan the way in which minor numbers are assigned to disk device group volumes. No two disk device groups can have overlapping minor number assignments.
Dirty Region Logging – The use of Dirty Region Logging (DRL) decreases volume recovery time after a node failure. Using DRL might decrease I/O throughput.
Dynamic Multipathing (DMP) – The use of DMP alone to manage multiple I/O paths per node to the shared storage is not supported. The use of DMP is supported only in the following configurations:
A single I/O path per node to the cluster's shared storage.
A supported multipathing solution, such as Sun Traffic Manager, EMC PowerPath, or Hitachi HDLM, that manages multiple I/O paths per node to the shared cluster storage.
See your VxVM installation documentation for additional information.