Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

389Administering cluster functionality
Overview of cluster volume management
Note: In this example, each node has two independent paths to the disks, which are
configured in one or more cluster-shareable disk groups. Multiple paths provide resilience
against failure of one of the paths, but this is not a requirement for cluster configuration.
Disks may also be connected by single paths.
The private network allows the nodes to share information about system resources and
about each other’s state. Using the private network, any node can recognize which other
nodes are currently active, which are joining or leaving the cluster, and which have failed.
The private network requires at least two communication channels to provide redundancy
against one of the channels failing. If only one channel were used, its failure would be
indistinguishable from node failure—a condition known as network partitioning.
Figure 13-1 Example of a 4-node cluster
VxVM objects configured within shared disk groups can potentially be accessed by all
nodes that join the cluster. However, the cluster functionality of VxVM requires that one
node act as the master node; all other nodes in the cluster are slave nodes. Any node is
Redundant SCSI or
Fibre Channel
connectivity
Node 0
(master)
Node 1
(slave)
Node 2
(slave)
Node 3
(slave)
Cluster-shareable disks
Redundant private network
Cluster-shareable disk
groups