Red Hat CLUSTER SUITE FOR ENTERPRISE LINUX 5.2 Guía de instalación descargar pdf (Pagina 15)

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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Red Hat CLUSTER SUITE FOR ENTERPRISE LINUX 5.2 Guía de instalación Pagina 15