When evaluating the design of your backup systems or developing a design of a new backup and recovery system, there are arguably only two metrics that matter: how fast you can recover, and how much data you will lose when you recover. If you build your design around the agreed-upon numbers for these two metrics, and then repeatedly test that you are able to meet those metrics in a recovery, you’ll be in good shape.
The problem is that few people know what these metrics are for their organization. This isn’t a matter of ignorance, though. They don’t know what they are because no one ever created the metrics in the first place. And if you don’t have agreed upon metrics (also known as service levels), every recovery will be a failure because it will be judged against the unrealistic metrics in everyone’s heads. With the exception of those who are intimately familiar with the backup and disaster recovery system, most people have no idea how long recoveries actually take.
Source:: Network World – Data Center