A Replicated Data Cluster (RDC) uses data replication, instead of shared storage (VMDg) or non-shared storage (VMNSDg), to assure data access to all the nodes in a cluster.

The Replicated Data Cluster configuration provides both local high availability and disaster recovery functionality in a single VCS cluster. You can set up RDC in a VCS environment using Volume Replicator.

An RDC exists within a single VCS cluster with a primary zone and a secondary zone, which can stretch over two buildings or data centers connected with Ethernet. In an RDC configuration, if an application or a system fails, the application is failed over to another system within the current primary zone. If the entire primary zone fails, the application is migrated to a system in the secondary zone (which then becomes the new primary).

For Volume Replicator replication to occur, the disk groups containing the Replicated Volume Group (RVG) must be imported at the primary and secondary zones. The replication service group must be online at both zones simultaneously, and must be configured as a hybrid VCS service group.

The application service group is configured as a failover service group. You must configure the application service group with an online local hard dependency on the replication service group.

An RDC configuration is appropriate in situations where dual dedicated LLT links are available between the primary zone and the secondary zone but lack shared storage (VMDg) or non-shared storage (VMNSDg) or SAN interconnect between the primary and secondary data centers. In an RDC, data replication technology provides node access to data in a remote zone.

You must use dual dedicated LLT links between the replicated nodes.