5.3.3. Creating Volume Groups in a Cluster

You create volume groups in a cluster environment with the vgcreate command, just as you create them on a single node.

By default, volume groups created with CLVM on shared storage are visible to all computers that have access to the shared storage. It is possible, however, to create volume groups that are local, visible only to one node in the cluster, by using the -c n option of the vgcreate command.

The following command, when executed in a cluster environment, creates a volume group that is local to the node from which the command was executed. The command creates a local volume named vg1 that contains physical volumes /dev/sdd1 and /dev/sde1.

# vgcreate -c n vg1 /dev/sdd1 /dev/sde1

You can change whether an existing volume group is local or clustered with the -c option of the vgchange command, which is described in Section 5.3.8, “Changing the Parameters of a Volume Group”.

You can check whether an existing volume group is a clustered volume group with the vgs command, which displays the c attribute if the volume is clustered. The following command displays the attributes of the volume groups VolGroup00 and testvg1. In this example, VolGroup00 is not clustered, while testvg1 is clustered, as indicated by the c attribute under the Attr heading.

# vgs
  VG            #PV #LV #SN Attr   VSize  VFree
  VolGroup00      1   2   0 wz--n- 19.88G    0
  testvg1         1   1   0 wz--nc 46.00G 8.00M

For more information on the vgs command, see Section 5.3.5, “Displaying Volume Groups”Section 5.8, “Customized Reporting for LVM”, and the vgs man page.