What Is Cluster Fencing?

Cluster fencing is a term referring to the isolation of a malfunctioning node in a computer cluster. By isolating or removing the malfunctioning node from the rest of the cluster, valuable data are protected from damage or loss.

Definition

A cluster is a group of computers that are connected together over a network, forming what is, in essence, a single computer. The individual components of the cluster---the individual connected computers---are referred to as "nodes."

Significance

Because of the way they are interconnected, the individual nodes in a computer cluster can have a great effect on the performance and stability of the other nodes. If one node fails or malfunctions, it could cause data loss or damage across the cluster.

Function

Cluster fencing typically happens automatically, as soon as the network becomes aware that a cluster has failed, which is generally instantaneous. The fenced node is either automatically powered off to protect the rest of the cluster, or it simply loses all in/out connectivity with the other nodes.

References

• Linuxtopia: Fencing
• Cluster Wiki: FAQ/Fencing