Data Backup Strategies

There are three basic types of backups: full, differential, and incremental.

Full Backup

A full backup copies all the files on a selected system: software files, data files, and system files. It clears the archive bit of each file after every session.

Incremental Backup

During an incremental backup, only those files that have been modified since the previous full or incremental backup are saved. The archive bit is cleared on those files that are backed up. Incremental backups are quicker than full backups. However, the restore time is much higher because to restore an entire system, the last full backup and every incremental backup since then is required.

Differential Backup

A differential backup saves only the files that have been changed since the last full backup has taken place. It does not save the files since the last incremental backup. The archive bit is not cleared, so the list grows larger each day until the next full backup. The advantage of differential backup is that when restoring to a previous state, only the last full backup and the most recent differential backup are needed.