Using Journal Archiving with Incremental Backups
Incremental backup improves both time and space restore requirements over journal archiving, but it’s not an either/or decision. You can, and should, use both where appropriate. If your goal is to be able to restore to any arbitrary point in time while minimizing potential data loss, follow these steps:
Configure a scheduled full backup at some coarse granularity (for example, weekly) and enable journal archiving.
Configure a scheduled incremental backup at some finer granularity (for example, every four hours), and specify
purge-journal-archiving=true.Set
retain until backupon the database Merge Policy so that deleted fragments are retained until they have been included in an incremental backup. See Setting Merge Policy oradmin:database-set-retain-until-backupfor details.
This configuration means that journal archives are only needed since the most recent incremental backup, and the older ones can be purged once there is another incremental backup. Enabling retain until backup ensures that the incremental backups have sufficient state to restore the database to any point since the previous incremental backup.
When you restore, the full and incremental backups can be used to return to any point in time prior to the most recent backup, and the journal archive will only be used if your restore point is more recent than the last incremental backup.