Components of high availability

High availability provides access to critical business applications and data in the event of a disruption in service. IBM® i high availability solutions minimize and sometimes eliminate the effect of planned and unplanned outages and site-wide disasters for your business. The basis for IBM i high availability solutions is cluster technology.

A cluster is two or more systems (or operating system images) that share resources and processing and provide backup in the event of an outage. With clustering, high availability is viewed not as a series of identical copies of the same resource across these systems but rather a set of shared resources that continually provide essential services to users and applications.

Clustering does not provide a complete high availability solution all by itself, but it is the key technology on which all IBM i high availability solutions are based. Clustering infrastructure, called cluster resource services, provides the underlying mechanisms for creating and managing multiple systems and their resources as one unified computing entity. Clustering also monitors systems and resources defined in the high availability environment for failures and responds accordingly, depending on the type of outage. Clustering combines hardware and software to reduce the cost and effect of planned and unplanned outages by quickly restoring services when these outages occur. Although not instantaneous, cluster recovery time is rapid.

The following section defines the key components of a high availability solution.