VERITAS Volume Manager 4.1 Administrator's Guide

Administering Cluster Functionality
Overview of Cluster Volume Management
Chapter 10356
NOTE The default activation mode for shared disk groups is off (inactive).
Special uses of clusters, such as high availability (HA) applications 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.
Table 10-1 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 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 nor write access
to the disk group. Query operations on the
disk group are permitted.