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

Cluster Volume Manager Administration

Overview of Cluster Volume Management

Chapter 4

• exclusive-write

• read-only

• shared-read

• shared-write

• off

To view the activation mode setting for each of your shared disk groups, enter:

# cfsdgadm display

When a shared disk group is created or imported, it is activated in the specified mode.

When a node joins the cluster, all shared disk groups accessible from the node are

activated in the specified mode.

If the defaults file is edited while the vxconfigd daemon is already running, the

vxconfigd process must be restarted for the changes in the defaults file to take effect.

If the default activation mode is anything other than off, an activation following a

cluster join, or an activation following a disk group creation (or import) will fail, if

another node in the cluster has activated the disk group in a conflicting mode.

To display the activation mode for a shared disk group, use the vxdg list diskgroup

command.

You can also use the vxdg command to change the activation mode on a shared disk

group.

Connectivity Policy of Shared Disk Groups

The nodes in a cluster must agree on the status of a disk, or a connectivity policy setting

will determine the disk status. If one node cannot write to a particular disk, all nodes

must stop accessing that disk before the results of the write operation are returned to

the caller. If a node cannot contact a disk, it must contact another node to check on the

disk’s status. If a disk fails, the nodes will agree to detach the disk, because no node can

access it. If a disk does not fail, but the access paths to that disk from some of the nodes

in the cluster fail, the nodes in the cluster will not be able to agree on the status of the

disk. In this case, one of the following connectivity policies will be applied:

• Under the global connectivity policy, the detach occurs cluster-wide (globally) if any

node in the cluster reports a disk connectivity failure. This is the default connectivity

policy.

• Under the local connectivity policy, if disk connectivity fails, the failure is confined to

the particular nodes that see the failure. An attempt is made to communicate with

all nodes in the cluster to determine the usability of the disks. If all nodes report a

problem with the disks, a cluster-wide detach occurs.

The vxdg command is used to set the disk detach and disk group failure policy. The

dgfailpolicy attribute sets the disk group failure policy in the case that the master

node loses connectivity to the configuration and to the log copies within a shared disk

group. This attribute requires that the disk group version is 120 or greater. The following

policies are supported:

• dgdisable—The master node disables the diskgroup for all user or kernel initiated

transactions. First write and final close fail. This is the default policy.