Red Hat CLUSTER SUITE FOR ENTERPRISE LINUX 5.2 Overview page 19

Fencing
Figure 1.4. Fibre Channel Switch Fencing Example
Specifying a fencing method consists of editing a cluster configuration file to assign a
fencing-method name, the fencing agent, and the fencing device for each node in the cluster.
The way in which a fencing method is specified depends on if a node has either dual power
supplies or multiple paths to storage. If a node has dual power supplies, then the fencing
method for the node must specify at least two fencing devices — one fencing device for each
power supply (refer to Figure 1.5, "Fencing a Node with Dual Power Supplies"). Similarly, if a
node has multiple paths to Fibre Channel storage, then the fencing method for the node must
specify one fencing device for each path to Fibre Channel storage. For example, if a node has
two paths to Fibre Channel storage, the fencing method should specify two fencing devices —
one for each path to Fibre Channel storage (refer to Figure 1.6, "Fencing a Node with Dual Fibre
Channel Connections").
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