failover

The transfer of control of an application or service from one node to another node after a failure. Failover can be manual, requiring human intervention, or automated, requiring little or no human intervention.

In the event of a physical disruption to a network component, data is immediately rerouted to an alternate path so that services remain uninterrupted. Failover applies both to clustering and to multiple paths to storage. In the case of clustering, one or more services (such as Exchange) is moved over to a standby server in the event of a failure. In the case of multiple paths to storage, a path failure results in data being rerouted to a different physical connection to the storage.

The process by which an alternate system takes over and emulates the primary system if the primary system becomes unusable.

A cluster's ability to redirect requests from one server to another. Failover occurs when a user tries to access an application on an unavailable server or one in heavy use, and the user instead connects to a replica on another (available) server in the cluster. Failover is transparent to the user.

A failover cluster provides high availability by making application software and data available on several servers linked together in a cluster configuration. If one server stops functioning, a process called failover automatically shifts the workload of the failed server to another server in the cluster. The failover process is designed to ensure continuous availability of critical applications and data. [Exchange 2007]

In a failover cluster or server cluster, the process of taking a clustered service or application offline on one node and bringing it back online on another node.