In the RDC set up for the Oracle database, consider a case where the primary RDC zone suffers a total failure of the shared storage. In this situation, none of the nodes in the primary zone see any device.
The Oracle service group cannot fail over locally within the primary RDC zone, because the shared volumes cannot be mounted on any node. So, the service group must fail over, to a node in the current secondary RDC zone.
The RVGPrimary agent ensures that VVR volumes are made writable and the DNS agent ensures that name services are resolved to the DR site. The application can be started at the DR site and run there until the problem with the local storage is corrected.
If the storage problem is corrected, you can switch the application to the primary site using VCS.