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Associating a volume set to an RDS

This section describes how to associate a volume set to an RDS. A volume set is a container object for a group of volumes that can be a part of a Multi-device File System (MDFS). Associating the volume set to an RDS enables you to replicate an MDFS. For more information about volume sets, see the Veritas Volume Manager Administrator's Guide.

The component volumes of a volume set have assigned indices. Applications use these indices to identify a component volume. To be able to successfully start applications on the Secondary if a disaster occurs, the component volumes of the volume set on the Secondary must have the same indices as those of the corresponding Primary volumes.

This section assumes that the volume set that is to be replicated already exists on the Primary. If the volume set does not exist on the Primary, create the volume set.

The volume set need not exist on the Secondary; however, if the volume set already exists on the Secondary, the volume set on the Secondary must have the same characteristics as the volume set on the Primary. That is, the volume sets must have the same name, the same count of component, and the component volumes must have the same names, sizes, and indices. If the volume set does not exist on the Secondary, and the component volumes do exist with the same names, sizes, and indices as on the Primary, the vradmin addvol command creates the volume set on the Secondary.

You cannot associate a volume set, or a component volume of a volume set, as an SRL.

After a volume set is associated to an RDS, the vradmin addvol command can be used to add an independent volume to the volume set. A component volume added to the volume set this way becomes a part of the RVG and is replicated.

By default, the vradmin addvol command adds DCM logs to the component volumes when a volume set is added to the RDS, if they have not already been added. If any of the data volumes contains a DRL log, the vradmin addvol command removes the DRL log before adding the DCM to the data volume. The -nodcm option with the vradmin addvol command adds component volumes to the RDS without adding DCMs to the volumes. If -nodcm is issued when any of the RLINKs has srlprot set to dcm or autodcm, and any of the volumes being added to the RDS does not already have a DCM log, the command will fail. This behavior is the same as for independent data volumes.

 To associate a volume set to an RDS

1. Verify whether the component volumes of the volume set on the Primary and its Secondaries have identical indices. To view the indices, use the following command:

   # vxvset -g diskgroup list vset_name

2. If the indices of the component volumes on the Primary volume set and Secondary volume set are identical, go to step 4.
3. If the indices of the component volumes on the Primary volume set and Secondary volume set are different, perform the following steps on the Secondary:
   1. Dissociate each volume from the volume set using the following command:

      # vxvset -g diskgroup rmvol vset_name compvol_name

      When you remove the last volume, the volume set is also removed.

   2. Create the volume set using the following command:

      # vxvset -g diskgroup -o index make vset_name \

compvol_name index

1. Associate each of the remaining volumes to the volume set specifying the index of the corresponding volumes on the Primary using the following command:

   # vxvset -g diskgroup -o index addvol vset_name \

compvol_name index

4. Associate the volume set to the RDS using the following command:

   # vradmin -g diskgroup addvol rvg_name vset_name

   ---

     Note   use the volume set name in the command, not the names of each component volume. Specifying the component volume name causes the command to fail.

   ---

Example:

This example shows how to associate the component volumes hr_cv1 and hr_cv2 of the volume set hr_vset to the RDS hr_rvg. The example assumes that the component volumes have identical indices.

1. Verify whether the component volumes of the volume set hr_vset on the Primary and its Secondaries have identical indices using the following command on the Primary and its Secondaries:

   # vxvset -g hrdg list hr_vset

   Output looks like this:

VOLUME   INDEX LENGTH KSTATE CONTEXT

hr_cv1 0 8388608 ENABLED -

hr_cv2 1 8388608 ENABLED -

2. Associate the component volumes hr_cv1 and hr_cv2 to the RDS hr_rvg using the following command:

   # vradmin -g hrdg addvol hr_rvg hr_vset

 To associate an independent volume to a volume set associated to an RDS

• Associate the volume set to the RDS using the following command:

  # vradmin -g diskgroup -tovset vset_name addvol rvg_name \

volume_name[:index]

If an index is specified, that index is used to add the volume to the volume set on all the hosts in the RDS. The command fails if the specified is already in use.

If an index is not specified, the vradmin addvol command ensures that the same index is used to add the volume to the volume set on all the hosts in the RDS.

Example:

This example shows how to associate the independent volume hr_cv3 to the volume set hr_vset, which is associated to the RDS hr_rvg.

• Associate the component volumes hr_cv3 to the volume set hr_vset using the following command:

  # vradmin -g hrdg -tovset hr_vset addvol hr_rvg hr_cv3