Over the past several months, I've been receiving a lot of questions about replication for continuity and recovery. One thing I've noticed, however, is that there is a lot of confusion around replication and its uses. To combat this, my colleague Stephanie Balaouras and I recently put out a research report called "The Past, Present, And Future Of Replication" where we outlined the different types of replication and their use cases. In addition to that, I thought it would be good to get some of the misconceptions about replication cleared up:
Myth: Replication is the same as high availability Reality: Replication can help to enable high availability and disaster recovery, but it is not a solution in and of itself. In the case of an outage, simply having another copy of the data at an alternate site isn't going to help if you don't have a failover strategy or solution. Some host-based replication products come with integrated failover and failback capabilities.
Myth: Replication is too expensive Reality: It's true that traditionally array-based replication has been expensive due to the fact that it requires like-to-like storage and additional licensing fees. However, two factors have mitigated this expense: 1) several storage vendors are no longer charging an extra licensing fee for replication; and 2) there are several alternatives to array-based replication that allow you to use heterogeneous storage and come at a significantly lower acquisition cost. Replication products fall into one of four categories (roughly from most to least expensive):