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

Cluster File System Administration
Cluster File System Overview
Chapter 3
32
Cluster File System Overview
With respect to each shared file system, a cluster includes one primary node, and up to 7
secondary nodes. The primary and secondary designation of nodes is specific to each file
system, not the hardware. It is possible for the same cluster node be primary for one
shared file system, while at the same time it is secondary for another shared file system.
Distribution of file system primary node designation to balance the load on a cluster is a
recommended administrative policy.
See “Distributing Load on a Cluster” on page 20.
For CVM, a single cluster node is the master node for all shared disk groups and shared
volumes in the cluster.
Cluster and Shared Mounts
A VxFS file system that is mounted is called a cluster or shared mount, as opposed to a
non-shared or local mount. A file system mounted in shared mode must be on a VxVM
shared volume in a cluster environment. A local mount cannot be remounted in shared
mode and a shared mount cannot be remounted in local mode. File systems in a cluster
can be mounted with different read-write options. These are called asymmetric mounts.
Cluster File System Primary and Cluster File System Secondary
Both primary and secondary nodes handle metadata intent logging for a cluster file
system. The first node of a cluster file system to mount is called the primary node - the
other nodes are called secondary nodes. If a primary node fails, an internal election
process determines which of the secondaries becomes the primary file system.
Use the following command to determine which node is primary:
# fsclustadm –v showprimary mount_point
Use the following command to designate a primary node:
# fsclustadm –v setprimary mount_point