Symantec Veritas 5 - Manual (Page 14)

Figure 1-1 illustrates a typical VCS configuration of four nodes that are connected
to shared storage.
Figure 1-1 Example of a four-node VCS cluster
Client workstation Client workstation
Public network
Shared storage
VCS private
network
VCS nodes
Client workstations receive service over the public network from applications
running on VCS nodes. VCS monitors the nodes and their services. VCS nodes in
the cluster communicate over a private network.
About multiple nodes
VCS runs in a replicated state on each node in the cluster. A private network
enables the nodes to share identical state information about all resources. The
private network also recognizes active nodes, the nodes that join or leave the
cluster, and failed nodes. The private network requires two communication
channels to guard against network partitions.
About shared storage
A VCS hardware configuration typically consists of multiple nodes that are
connected to shared storage through I/O channels. Shared storage provides
multiple systems with an access path to the same data. It also enables VCS to
restart applications on alternate nodes when a node fails, which ensures high
availability.
VCS nodes can only access physically-attached storage.
Figure 1-2 illustrates the flexibility of VCS shared storage configurations.
Introducing Veritas Cluster Server
About VCS basics 14