Traditionally, your options for getting data off-site for disaster recovery were limited to shipping tapes or real-time data replication. Since tape shipping results in recovery point objectives (RPOs) and recovery time objectives (RTOs) of hours at best, and days in most cases, and real-time replication is expensive, there was a real lack of a middle ground.

As de-duplicating backup appliances, including those from Sepaton, Quantum, Data Domain, and FalconStor (including OEMs from Copan to EMC and Sun) started to support the replication of de-duplicated data, that middle ground may be here.

Since backup appliances, whether NAS or VTL, only have data to replicate after you run a backup, RPO is still limited to your backup frequency of once a day. If you set up real-time replication for your mission-critical applications, you'll size the link between your primary and DR sites to deal with middle of the day traffic levels.

In the middle of the night when your backups run, and the appliances replicate, some of that bandwidth will be available. The data de-duplication that backup appliances apply, because it runs on files in their static state, does a much better job of sending just the changed portions of files than any host-based replication software.

So what do you think? Good idea or strange fever dream?