Volume Replicator is configured such that the volumes to be replicated for a specific application are placed in an RVG. Writes to the data volumes are persistently queued in the Replicator Log volume. Volume Replicator uses the Replicator Log volume to track all the writes in the order in which they were received and Volume Replicator transmits the writes to the Secondary using the replication link (RLINK). You can choose to use either the UDP protocol or TCP protocol for network communication between the Primary and Secondary.

The Replicator Log volume is a SFW volume that is configured as part of an RVG. On the Primary, each write to an RVG generates two writes; first to the Replicator Log volume and then to the data volume. Only the write to the Replicator Log volume affects the application. The write to the data volume is written in the background and does not affect application performance.

If the Primary crashes at any point before the write to the data volume is completed, data is fully recoverable from the Replicator Log volume. This is very similar to a database writing to a redo log and later writing to the data files.