Choosing a Backup Level

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Choosing a Backup Level

The ontape utility supports level-0, level-1, and level-2 backups. For information on scheduling backups, see Planning a Recovery Strategy.

Tip:

It is good practice to create a backup schedule that keeps level-1 and level-2 backups small and to schedule frequent level-0 backups. With such a backup schedule, you avoid having to restore large level-1 and level-2 backups or many logical-log backups.

Level-0 Backups

When a fire or flood, for example, completely destroys a computer, you need a level-0 backup to completely restore database server data on the replacement computer. For online backups, the data on the backup tape reflects the contents of the storage spaces at the time the level-0 backup began. (The time the backup started could reflect the last checkpoint before the backup started.)

A level-0 backup can consume lots of time because ontape must write all the pages to tape.

Level-1 Backups

A level-1 backup usually takes less time than a level-0 backup because you copy only part of the database server data to the backup tape.

Level-2 Backups

A level-2 backup after a level-1 backup usually takes less time than another level-1 backup because only the changes made after the last level-1 backup (instead of the last level-0) get copied to the backup tape.