Veritas Storage Foundation 5.1 SP1 Cluster File System Administrator"s Guide (5900-1738, April 2011)

primary mounts "ro". Otherwise, the primary mounts either "rw" or "ro,crw", and
the secondaries have the same choice.
You can specify the cluster read-write (crw) option when you first mount the file
system, or the options can be altered when doing a remount (mount -o remount).
See the mount_vxfs(1M) manual page.
Figure 2-1 describes the first column showing the mode in which the primary is
mounted:
Figure 2-1
Primary and secondary mounts
The check marks indicate the mode secondary mounts can use for a given mode
of the primary.
Mounting the primary with only the -o cluster,ro option prevents the
secondaries from mounting in a different mode; that is, read-write.
Note: rw implies read-write capability throughout the cluster.
Primary and secondary
A file system cluster consists of one primary, and up to 63 secondaries. The
primary-secondary terminology applies to one file system, not to a specific node
(or hardware platform). You can have the same cluster node be primary for one
shared file system, while at the same time it is secondary for another shared file
system. Such distribution of file system primaryship to balance the load on a
cluster is a recommended administrative policy.
See “Distribute the load on a cluster” on page 61.
23Storage Foundation Cluster File System architecture
Primary and secondary