On the surface, the idea of deduplicated replication is compelling. By replicating deltas, the technology sends data across a WAN and dramaically reduces the required bandwidth. Many customers are looking to this technology to allow them to move to a tapeless environment in the future. However, there is a major challenge that most vendors gloss over.
The most common approach to deduplication in use today is hash-based technology which uses reverse referencing. I covered the implications of this approach in another post. To summarize, the issue is that restore performance is impacted as data is retained in a reverse referenced environment. Now let’s look at how this impacts deduplicated replication.