18.4 Summary

Backups play a critical role in protecting your data from both intentional and inadvertent destruction. Backups also protect from system failures, computer destruction, and natural disaster. Good backups can also be a powerful tool in recovering from a break-in: backups allow you to determine what an attacker has changed and what remains safe.

Nevertheless, time and again we see sites that do not have adequate backups. These sites might back up some of their servers, but leave others unprotected. Central IT officials might back up all of their servers, but leave desktop users to fend for themselves. System administrators might believe that operating systems and applications can be restored from distribution media and back up only their "data"—without realizing that site-specific configuration information is not being backed up as part of their procedures. Or sites might invest in expensive RAID systems and then neglect to back up anything at all—without realizing that RAID protects only against hardware failure; it does nothing to protect against accidental file deletion or software failure.

Several chapters of this book were accidentally deleted or corrupted while it was being written. We were able to recover the book through the use of our backups. Time and time again, backups prove their worth. There are many acts of destruction that you simply cannot foresee or prevent. With good backups, you can at least recover from a catastrophe.