HP UX Serviceguard Storage Management Software manual Cluster File System Overview

Cluster File System Administration

Cluster File System Overview

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

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