Incremental Backups Minimizing Backup Resources

Frequent backups can help you immensely in the event of data loss, but creating backups can be time-consuming. A tape drive capable of 6MB/s data transfers takes close to 4 hours to back up 80GB of data. Media capacity is also an issue. As your storage needs grow, so do your backup needs, and changing from one backup medium to another can be costly. Therefore, you probably want to stretch the life of your media as much as possible, and that means minimizing the amount of data you back up on a regular basis. Finally, if you maintain a network of computers, backups can consume a great deal of network bandwidth, robbing you of the use of that bandwidth for other purposes. For all of these reasons, a technique known as incremental backup is popular. Incremental backups enable you to back up everything once and then back up only new or changed files on subsequent backups. Of course, sooner or later you'll want to perform a new full backup. Understanding the types of incremental backups and schedules for their use can help you to plan the backup strategy that's best for your needs. Most backup programs support incremental backups. As an example, I describe tar's incremental backup options.

Note The Linux cp command doesn't provide any incremental backup options. On the other end of the scale, AMANDA provides extensive incremental backup tools; in fact, it's designed to work only in a special incremental backup mode that spreads network resource usage out overtime.

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