RMAN – Configuring Archivelog Deletion Policy

RMAN Deletion Policy Tips
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Expert Oracle Database Tips by Donald BurlesonMarch 25, 2015

Configuring Archivelog Deletion Policy

Archivelogs are not just used for the recovery of the primary database, they are also often used with the standby environments. Over these environments, it is important to keep the archivelogs as long as they are not shipped to the standby server, making it synchronized with the primary server.

Using the configure command, you can set the deletion policies for the archivelogs to say when they should get deleted. There are three possible options for this:

• applied on standby
  applied on standby gets the archivelogs deleted only after they are applied over the standby database as well.

• none
  none lets the archivelogs be deleted once they exceed the retention policy that you have set for them.

• clear
  clear would revert back the configured settings to the default one, none.

Configuring the Snapshot Control File

The snapshot control file is a temporary file that is created at a certain location specified over the operating system. This file is used by RMAN to synchronize the information with the current control file. This file, except for synchronizing the information with the current control file, does not do anything else and hence, is not included in the recovery catalog. It does not contain any information about the current backup that you have taken, though it does know about the last backups that were done and are not marked yet as obsolete. So this file can be used to recover a scenario where you have lost everything and also were not using the catalog. You can use the last backup information recorded in this file and can recover the database with that backup.

The location of this file depends on the platform and also uses a default naming convention as well. Interestingly, irrespective of the flash recovery area being configured, the snapshot control file does not use it and is set for the location, normally to the ORACLE_HOME/database or ORACLE_HOME/dbs location with the name sncf.ora.