Backup Media Requirements

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A backup rotation scheme allows some media to be reused once the retention period of the job stored on it has expired.

Grandfather-Father-Son (GFS)

• most common rotation scheme
• labels the backup tapes in generations
  • Grandfather = monthly full backup
  • Father = weekly full backup
  • Son = daily incremental backup
• Son tapes store the most recent data and have the shortest retention period
• Grandfather tapes are the oldest and have the longest retention period

Implementation

1. A full backup is performed each week on Friday night to one of the tapes marked “Father.” As some months will have five Fridays, this requires five tapes labeled and dedicated to the father role.

2. Incremental backups are made during each day to a tape marked “Son,” using whatever frequency is required (every 15 minutes or every hour, for instance). The five son tapes are reused each week in the same order.

3. A full backup is performed at the end of the last working day of the month on a tape marked “Grandfather.” Twelve grandfather tapes are required.

4. The father tapes are then reused for the next month in the same order, and the cycle continues. At the end of the year, the first grandfather tape is overwritten.

On Site vs Off Site Storage

On site backup storage means that the production system and backup media are in the same location.

• risk of losing both the production and backup copies of data

A media rotation scheme such as GFS means that at least some of the backup media can be taken for storage off site once the backup job has run.

Online vs Offline Backups

Online backup media is instantly available to perform a backup or restore operation without an administrator having to transport and connect a device or load a tape.

• faster

An offline backup device is kept disconnected from the host and must be connected manually to run a backup job.

• better security
• should keep at least one backup copy offline