Managing Serviceguard 12th Edition, March 2006

Understanding Serviceguard Software Components
How the Cluster Manager Works
Chapter 372
three-node cluster is removed for maintenance, the cluster reforms as a
two-node cluster. If a tie-breaking scenario later occurs due to a node or
communication failure, the entire cluster will become unavailable.
In a cluster with four or more nodes, you may not need a cluster lock
since the chance of the cluster being split into two halves of equal size is
very small. However, be sure to configure your cluster to prevent the
failure of exactly half the nodes at one time. For example, make sure
there is no potential single point of failure such as a single LAN between
equal numbers of nodes, or that you don’t have exactly half of the nodes
on a single power circuit.