The figure shows clients, including Oracle Identity Management and middle tiers, using a virtual hostname or virtual IP to access two nodes (node 1 and node 2) in a hardware cluster. Node 1 is the active node, and node 2 is the standby node.
Each node runs vendor clusterware. Both nodes can access a shared storage which contains the Oracle home for the database and the data files for the database, but only one node (the active node) can mount the shared storage at any time.
Usually node 1 (the active node) runs the database processes. If node 1 fails, then a failover event occurs and node 2 becomes the active node, mounts the shared storage, and runs the database processes. The virtual hostname and IP also change to point to node 2.