Practical UNIX and Internet Security, 3rd Edition

Why Make Backups?

Backups are important only if you value the work that you do on your computer. If you use your computer as a paperweight, then you don’t need to make backups.

Years ago, making daily backups was a common practice because computer hardware would often fail for no obvious reason. A backup was the only protection against data loss. Today, hardware failure is still a good reason to back up your system. Hard disk failures are a random process: even though a typical hard disk will now last for five years or more, an organization that has 20 or 30 hard disks can expect a significant drive failure every few months. Drives frequently fail without warning—sometimes only a few days after they have been put into service. It’s prudent, therefore, to back up your system on a regular basis.

Backups can also be an important tool for securing computers against attacks. Specifically, a full backup allows you to see what an intruder has changed by comparing the files on the computer with the files on the backup. We recommend that you make your first backup of your computer after you install its operating system, load your applications, and install all of the necessary security patches. Not only will this first backup allow you to analyze your system after an attack to see what has been modified, but it will also save the time of rebuilding your system from scratch in the event of a hardware failure.

The Role of Backups

Backups serve many different purposes in a typical organization: ...