To use the Secondary in a disaster recovery scenario, write-order fidelity must be maintained. The term write-order fidelity means that Volume Replicator tracks writes on the Primary in the order in which they are received and applies them on the Secondary in the same order. It is important to maintain write-order fidelity to ensure that the data on the Secondary is consistent with the data on the Primary. While the data at the Secondary can be behind in time, it must be a consistent image of the Primary at a known point in the past.

Without write-order fidelity, there is no guarantee that a Secondary has consistent, recoverable data. Volume Replicator maintains write-order fidelity across all the data volumes that are covered under replication, regardless of the modes of replication that are used. For example, in a database environment, the log and data are typically on different volumes. On the Primary, Volume Replicator tracks the order of the writes that are made to the log and data volumes and maintains this order when applying the writes on the Secondary. If the write-order fidelity is not maintained, the database application may not recover successfully when failed over to the Secondary.