What is a VCS Cluster?

A VCS cluster is composed of a set of systems that provide scalability and high availability for specified applications. VCS monitors and controls the applications in a cluster, and can restart or move them in response to a variety of hardware and software faults. A cluster consists of multiple systems connected with a dedicated communications infrastructure. This infrastructure enables cluster members to exchange information on the status of cluster resources.

Each cluster has a unique cluster ID. Systems in a cluster are connected by redundant cluster communication links. Clusters can have from 1 to 32 member systems, or nodes. Applications can be configured to run on specific nodes within the cluster. Nodes can be individual systems, or they can be created with domains or partitions on enterprise-class systems. Individual cluster nodes each run their own operating system and possess their own boot device. Each node must run the same operating system within a single VCS cluster.

Most applications in a cluster require access to shared application data for systems hosting the application. Nodes sharing storage access are eligible to run an application. Nodes without common storage cannot fail over an application that stores data to disk. See Defining Cluster Topologies for details.