The Replicated Data Cluster (RDC) configuration provides both local high availability and disaster recovery functionality in a single VCS cluster.
This chapter describes how to setup RDC in a VCS environment using Veritas Volume Replicator (VVR.)
A Replicated Data Cluster (RDC) uses data replication to assure data access to nodes. An RDC exists within a single VCS cluster. In an RDC configuration, if an application or a system fails, the application is failed over to another system within the current primary site. If the entire primary site fails, the application is migrated to a system in the remote secondary site (which then becomes the new primary).
For VVR replication to occur, the disk groups containing the Replicated Volume Group (RVG) must be imported at the primary and secondary sites. The replication service group must be online at both sites simultaneously, and must be configured as a hybrid VCS service group.
The application service group is configured as a failover service group. The application service group must be configured with an online local hard dependency on the replication service group.
Note VVR supports multiple replication secondary targets for any given primary. However, RDC for VCS supports only one replication secondary for a primary.
An RDC configuration is appropriate in situations where dual dedicated LLT links are available between the primary site and the disaster recovery secondary site but lacks shared storage or SAN interconnect between the primary and secondary data centers. In an RDC, data replication technology is employed to provide node access to data in a remote site.
Note You must use dual dedicated LLT links between the replicated nodes.