Veritas Storage Foundation 5.0 Cluster File System Administration Guide Extracts for HP Serviceguard Storage Management Suite, Second Edition, May 2008

Cluster Volume Manager Administration
Overview of Cluster Volume Management
Chapter 4
43
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 cluster node, if it is activated in a
conflicting mode on another node in the cluster.
The following table 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 defaults file /etc/default/vxdg must be created.
The defaults file /etc/default/vxdg must contain the following lines:
enable_activation=true
default_activation_mode=activation-mode
Where activation-mode is one of the following:
Table 4-1 Activation Modes for Shared Disk Groups
Activation Mode Description
exclusive-write
(ew)
The node has exclusive write access to the disk group. No other
node can activate the disk group for write access.
read-only (ro) The node has read access to the disk group and denies write
access for all other nodes in the cluster. The node has no write
access to the disk group. Attempts to activate a disk group for
either of the write modes on other nodes will fail.
shared-read (sr) The node has read access to the disk group. The node has no
write access to the disk group, however other nodes can obtain
write access.
shared-write (sw) The node has write access to the disk group.
off The node has neither read or write access to the disk group.
Query operations on the disk group are permitted.
Table 4-2 Allowed and Conflicting Activation Modes
Disk group
activated in
cluster as...
Attempt to activate disk group on another node as...
exclusive-
write
read-only shared-read shared-write
exclusive-wr
ite
Fails Fails Succeeds Fails
read-only Fails Succeeds Succeeds Fails
shared-read Succeeds Succeeds Succeeds Succeeds
shared-write Fails Fails Succeeds Succeeds