When it comes to Oracle database administration, one of the most revered parts of your database structure is the fast recovery area (FRA). This is an Oracle managed area where DBAs usually store some of the following files:
- Redo logs
- Archive logs
- Flashback logs
- Control files
- RMAN backups
The purpose of the FRA is to simplify database recovery. The Oracle database process automatically manages items stored in the FRA and will delete items that are no longer needed.
Now the FRA may sound like a magical area that should never run into storage-related issues—but that could not be farther from the truth. Even though the Oracle database process will manage items and attempt to delete files that aren’t needed, the DBA also has to be aware of instance settings that may block Oracle from being able to remove the files. Some settings that can cause storage issues with your FRA include:
- RMAN backup retention setting – If you set your backup retention to store two weeks’ worth of RMAN backups, but your FRA fills up to 100% before any backups can be purged, this will cause your database to halt.
- RMAN archive log deletion policy – If you set the deletion policy to delete archive logs after they are applied to all standby databases, but haven’t noticed that your primary and standby databases have been out of sync for a long period of time, your FRA can fill to 100% and cause your database to halt.
- RMAN archive log backup copies setting – By default, backup copies are set to 1. But what if you want to make sure your backups contain more copies of your archive logs in the event that one of your incremental backups became corrupted? When you set this setting higher than 1, you will not be able to delete any archive logs unless they have been backed up however many times this setting is set to. So if you set this option to 3, you will need to have taken at least three backups of each archive log before said log can be deleted from your system. If you opted to store archive logs in your FRA, then this can fill the FRA to 100% and cause your database to halt.
- Db_flashback_retention_target setting – If you have enabled the flashback database option this is stored in the FRA by default. As with the archive logs, depending on the time value of the setting, it will store all flashback logs needed to guarantee that you can flashback your database as per the setting. If you set this to a high setting, this can fill the FRA to 100% and cause your database to halt.
Those are just a handful of the many ways you can accidentally fill your FRA, which is why you need to make sure that your FRA is adequately sized to store all files as per all retention settings. You should also create a script that queries the v$recovery_area_usage and have this result sent to the email of all DBAs, as this will tell you how much of your FRA is used and what in particular is taking up the space:
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