To understand how a replicated data cluster configuration works, let us take the example of an Oracle database configured in a VCS RDC. The configuration has two system zones:
Oracle is installed and configured on all nodes in the cluster. Oracle data is located on shared disks within each RDC zone and is replicated across RDC zones to ensure data concurrency. The Oracle service group is online on a system in the current primary zone and is configured to fail over in the cluster.
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In the event of a system or application failure, VCS attempts to fail over the Oracle service group to another system within the same RDC zone. However, in the event that VCS fails to find a failover target node within the primary RDC zone, VCS switches the service group to a node in the current secondary RDC zone (zone 1). VCS also redirects clients once the application is online on the new location.