Installation guide

the node votes plus 1. For quorum via quorum disk, quorum consists of user-specified
conditions.
Note
By default, each node has one quorum vote. Optionally, you can configure each
node to have more than one vote.
CMAN keeps track of membership by monitoring messages from other cluster nodes. When
cluster membership changes, the cluster manager notifies the other infrastructure components,
which then take appropriate action. For example, if node A joins a cluster and mounts a GFS file
system that nodes B and C have already mounted, then an additional journal and lock
management is required for node A to use that GFS file system. If a cluster node does not
transmit a message within a prescribed amount of time, the cluster manager removes the node
from the cluster and communicates to other cluster infrastructure components that the node is
not a member. Again, other cluster infrastructure components determine what actions to take
upon notification that node is no longer a cluster member. For example, Fencing would fence
the node that is no longer a member.
Figure 1.2. CMAN/DLM Overview
3.2. Lock Management
Lock management is a common cluster-infrastructure service that provides a mechanism for
other cluster infrastructure components to synchronize their access to shared resources. In a
Red Hat cluster, DLM (Distributed Lock Manager) is the lock manager. As implied in its name,
DLM is a distributed lock manager and runs in each cluster node; lock management is
Lock Management
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