ServerBuddies Support Blog

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 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.

You can change whether an existing volume group is local or clustered with the -c option of the vgchange command.

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.

EXAMPLES

To create a volume group named test_vg using physical volumes /dev/hdk1, and /dev/hdl1 with default physical extent size of 4MB:

Creating Volume Groups

To create a volume group from one or more physical volumes, use the vgcreate command. The vgcreate command creates a new volume group by name and adds at least one physical volume to it.

DESCRIPTION

vgcreate creates a new volume group called VolumeGroupName using the block special device PhysicalVolumePath previously configured for LVM with pvcreate(8).

The following command creates a volume group named vg1 that contains physical volumes /dev/sdd1 and /dev/sde1.

When physical volumes are used to create a volume group, its disk space is divided into 4MB extents, by default. This extent is the minimum amount by which the logical volume may be increased or decreased in size. Large numbers of extents will have no impact on I/O performance of the logical volume. You can specify the extent size with the -s option to the vgcreate command if the default extent size is not suitable.

EXAMPLES

To create a volume group named test_vg using physical volumes /dev/hdk1, and /dev/hdl1 with default physical extent size of 4MB: