Veritas Storage Foundation 5.0.1 Cluster File System Administrator's Guide Extracts for the HP Serviceguard Storage Management Suite on HP-UX 11i v3

# fsclustadm –v showprimary mount_point
To determine if the CFS primary is also the CVM master node, enter:
# vxdctl -c mode
To increase the size of the file system, run the following commands: On the CVM master node,
enter:
# vxassist -g shared_disk_group growto volume_name newlength
On any CFS node, enter:
# fsadm –F vxfs –b newsize –r device_name mount_point
The fstab file
In the /etc/fstab file, do not specify any cluster file systems to mount-at-boot, because
mounts initiated from fstab occur before cluster configuration begins. For cluster mounts, use
the HP Serviceguard configuration file to determine which file systems to enable following a
reboot.
Distributing the Load on a Cluster
Distributing the workload in a cluster provides performance and failover advantages. For example,
if you have eight file systems and four nodes, designating two file systems per node as primary
file systems will be beneficial. Primaryship is determined by which node first mounts the file
system. You can also use the fsclustadm setprimary command to designate a CFS primary
node. In addition, the fsclustadm setprimary command can define the order in which
primaryship is assumed if the current primary node fails. After setup, the policy is in effect as
long as one or more nodes in the cluster have the file system mounted.
Snapshots for Cluster File Systems
A snapshot provides a consistent point-in-time image of a VxFS file system. A snapshot can be
accessed as a read-only mounted file system to perform efficient online backups. Snapshots
implement copy-on-write semantics that incrementally copy data blocks when they are overwritten
on the “snapped” file system.
Snapshots for Serviceguard cluster file systems extend the same copy-on-write mechanism for
the I/O originating from any node in a CFS cluster.
Cluster Snapshot Characteristics
• A snapshot for a cluster mounted file system can be mounted on any node in a cluster. The
file system node can be a primary, secondary, or secondary-only node. A stable image of
the file system is provided for writes from any node.
• Multiple snapshots of a cluster file system can be mounted on the same node, or on a different
node in a cluster.
• A snapshot is accessible only on the node it is mounted on. The snapshot device cannot be
mounted on two different nodes simultaneously.
• The device for mounting a snapshot can be a local disk or a shared volume. A shared volume
is used exclusively by a snapshot mount and is not usable from other nodes in a cluster as
long as the snapshot is active on that device.
• On the node mounting a snapshot, the “snapped” file system cannot be unmounted while
the snapshot is mounted.
• A CFS snapshot ceases to exist if it is unmounted, or the node mounting the snapshot fails.
A snapshot is not affected if any other node leaves or joins the cluster.
• A snapshot of a read-only mounted file system cannot be taken. It is possible to mount a
snapshot of a cluster file system only if the “snapped” cluster file system is mounted with
the crw option.
Snapshots for Cluster File Systems 27