Storage Area Networks: Designing and Implementing a Mass Storage System

6.3. The Painful Rules of Backup

All backup and restore operations, including SAN backup and restore operations, are subject to the “Painful Rules of Backup.” These rules must have been formulated by a man named Murphy, who recognized that the universe is far from perfect.

• Rule 1. You will have a loss of data.

  You don’t know where. You don’t know when. However, it will happen. You will lose important data. Either file corruption, accidental overwriting, accidental deletion, deliberate deletion, device failure, or volcanic eruption will make some data unavailable.

  There’s a great data processing cartoon from the 1970s showing a distraught programmer being consoled by two others. The caption went something to the effect: “Well, you can recode it ...