VVR technology in disaster recovery
In NetBackup Flex Scale, the NetBackup catalog is replicated using Veritas Volume Replicator (VVR). VVR is a block level replication software. A consistency group of volumes is created on the source location and remote location. In VVR terminology, consistency group is known as Replicated Volume Group (RVG). VVR replicates data from a primary RVG on the primary site to the secondary RVG on the secondary site. VVR maintains write-order fidelity to guarantee consistent and recoverable copy of data on secondary site.
RVG consists of following components:
RLINK: Establishes the replication link between primary and secondary RVG.
SRL: Storage Replicator Log is a circular buffer of all the writes for an RVG. SRL enables VVR to maintain write-order fidelity at the secondary site.
Data Volumes: Group of related volumes.
DCM: Data Change Map is a component of VVR which is used to track application writes when the SRL overflows. This enables VVR to avoid complete resynchronization of the data on the secondary. DCM is only active on the primary site.