Veritas Storage Foundation 5.1 SP1 Cluster File System Administrator"s Guide (5900-1738, April 2011)

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 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 2-3
Example of a four node cluster
Redundant Fibre
Channel Connectivity
Cluster-Shareable Disks
Redundant Private Network
Node 0
(master)
Node 1
(slave)
Node 2
(slave)
Node 3
(slave)
Cluster-Shareable Disk Groups
To the cluster monitor, all nodes are the same. 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 one node to act as the master
node; all other nodes in the cluster are slave nodes. Any node is capable of being
the master node, which is responsible for coordinating certain VxVM activities.
VxVM designates the first node to join a cluster the master node. If the master
node leaves the cluster, one of the slave nodes is chosen to be the new master. In
the preceding example, node 0 is the master node and nodes 1, 2 and 3 are slave
nodes.
Shared disk groups overview
This section provides an overview of shared disk groups.
This section includes the following topics:
47Storage Foundation Cluster File System architecture
About Veritas Volume Manager cluster functionality