A shared disk group must be activated on a node for the volumes in the disk group to become accessible for I/O from that node. The ability of applications to read from or to write to volumes is determined by the activation mode of a shared disk group. Valid activation modes for a shared disk group are exclusive-write
, read-only
, shared-read
, shared-write
, and off
(inactive).
Note
The default activation mode for shared disk groups is off
.
Applications such as high availability and off-host backup can use disk group activation to explicitly control volume access from different nodes in the cluster.
The activation mode of a disk group controls volume I/O from different nodes in the cluster. It is not possible to activate a disk group on a given node if it is activated in a conflicting mode on another node in the cluster.
Activation modes for shared disk groups describes Activation modes for disk groups.
Allowed and conflicting activation modes summarizes allowed and conflicting activation modes or shared disk groups:
Shared disk groups can be automatically activated in any mode during disk group creation or during manual or auto-import.
To control auto-activation of shared disk groups
The activation-mode
is one of exclusive-write
, read-only
, shared-read
, shared-write
, or off
.
When enabling activation using the defaults file, it is advisable that the defaults file be identical on all nodes in the cluster. Otherwise, the results of activation are unpredictable.
When a shared disk group is created or imported, it is activated in the specified mode. When a node joins the cluster, all shared disk groups accessible from the node are activated in the specified mode.
If the defaults file is edited while the vxconfigd
daemon is already running, the vxconfigd
process must be restarted for the changes in the defaults file to take effect.
Note
If the default activation mode is anything other than off
, an activation following a cluster join, or a disk group creation or import can fail if another node in the cluster has activated the disk group in a conflicting mode.
To display the activation mode for a shared disk group, use the vxdg
list
diskgroup
command.
You can also use the vxdg
command to change the activation mode on a shared disk group.