Failover is the process by which the cluster automatically relocates an application from a failed primary node to a designated redundant secondary node. Failover applications have the following characteristics:
Capable of running on only one node of the cluster
Dependent on the cluster framework for high availability
If the fault monitor detects an error, it either attempts to restart the instance on the same node, or to start the instance on another node (failover), depending on how the data service has been configured. Failover services use a failover resource group, which is a container for application instance resources and network resources (logical hostnames). Logical hostnames are IP addresses that can be configured up on one node, and later, automatically configured down on the original node and configured up on another node.
Clients might have a brief interruption in service and might need to reconnect after the failover has finished. However, clients are not aware of the change in the physical server that is providing the service.