Sun Cluster Software Installation Guide for Solaris OS

Global Fencing

Fencing is a mechanism that is used by the cluster to protect the data integrity of a shared disk during split-brain situations. By default, the scinstall utility in Typical Mode leaves global fencing enabled, and each shared disk in the configuration uses the default global fencing setting of pathcount. With the pathcount setting, the fencing protocol for each shared disk is chosen based on the number of DID paths that are attached to the disk.

In Custom Mode, the scinstall utility prompts you whether to disable global fencing. For most situations, respond No to keep global fencing enabled. However, you can disable global fencing to support the following situations:

Caution – Caution –

If you disable fencing under other situations than the following, your data might be vulnerable to corruption during application failover. Examine this data corruption possibility carefully when you consider turning off fencing.

If you disable global fencing during cluster configuration, fencing is turned off for all shared disks in the cluster. After the cluster is configured, you can change the global fencing protocol or override the fencing protocol of individual shared disks. However, to change the fencing protocol of a quorum device, you must first unconfigure the quorum device. Then set the new fencing protocol of the disk and reconfigure it as a quorum device.

For more information about fencing behavior, see Failfast Mechanism in Sun Cluster Concepts Guide for Solaris OS. For more information about setting the fencing protocol of individual shared disks, see the cldevice(1CL) man page. For more information about the global fencing setting, see the cluster(1CL) man page.