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About shared disk groups

This section highlights general information to refer to when dealing with disk groups and volumes. Refer to the Veritas Volume Manager documentation for complete details on creating and managing shared disk groups.

Viewing information on a disk group

To display information about a specific disk group, type:

vxdg list disk_group

Checking the connectivity policy on a shared disk group

By default, the connectivity policy for a shared disk group is set to "global." This setting protects against possible data corruption and causes all nodes to detach from the disk group when any node reports a disk failure for that disk group.

The output of the vxdg list shared_disk_group command includes the following line:

detach-policy: global

To change the connectivity policy for a disk group from "local" to "global," type:

# vxedit -g shared_disk_group set diskdetpolicy=global shared_disk_group

Determining whether a node is CVM master or slave

To determine whether a node is the CVM master or slave, type:

# vxdctl -c mode

On nebula, which is the slave, the output shows:

mode: enabled: cluster active - SLAVE

master: galaxy

On galaxy, which is the master, the output shows:

mode: enabled: cluster active - MASTER

master:galaxy

Deporting and importing shared disk groups

Shared disk groups in an SF Oracle RAC environment are configured for "Autoimport" at the time of CVM startup. If the user manually deports the shared disk group on the CVM master, the disk group is deported on all nodes. To reimport the disk group, the user must import the disk group as a shared group from the CVM master.

To deport a shared disk group, use the following command on the CVM master:

vxdg deport shared_disk_group

To import a shared disk group, use the following command on the CVM master:

vxdg -s import shared_disk_group

To import a disk group as a standalone disk group, deport it from the CVM master and use the following command on any node:

vxdg -C import shared_disk_group

To reimport a disk group as a shared disk group, deport it from the standalone node and use the following command on the CVM master node:

vxdg -C -s import shared_disk_group

Reviewing limitations of shared disk groups

The cluster functionality of VxVM (CVM) does not support RAID-5 volumes or task monitoring for shared disk groups in a cluster. These features can function in private disk groups attached to specific nodes of a cluster. Online relayout is available provided it does not involve RAID-5 volumes.

CVM only provides access to raw device; it does not support shared access to file systems in shared volumes unless you install and configure the appropriate software, such as CFS.