Failure fencing is a term used to indicate how shared data is protected in the event of a failure within the cluster. For example, if the interconnect fails or a node leaves the cluster unexpectedly, the cluster framework must ensure that the non-cluster nodes do not have access to shared storage. Locking out non-cluster members from shared storage removes the possibility of data corruption (and also prevents multiple clusters from forming).
This section explains failure fencing scenarios for node failures; however, the same mechanisms are used during routine SC2.2 operations (such as when a node joins or leaves the cluster).
Failure fencing should not be confused with cluster membership because ...