Dataguard or RMAN: Archivelog deletions when you have standby databases

Normally, archived redo log files in a flash recovery area that were backed up to a tertiary device or made obsolete (as defined by the RMAN retention policy) are eligible for deletion.

The archived redo log files that are backed up or obsolete can eventually be deleted automatically to make space if the disk space in the flash recovery area becomes full.

However, you can change this default deletion policy using the following

RMAN command:CONFIGURE ARCHIVELOG DELETION POLICY TO [CLEAR | NONE | APPLIED ON STANDBY];

This will be especially useful when you have bunch of archivelogs and you are unable to deterime which archives applied or not, Further, there will be cases when you have manually recovered the archive logs using recover standby rather managed recovery and the v$archived_log applied column will be marked as "NO"

APPLIED ON STANDBY:-

CLEAR Clause

Use the CLEAR clause to disable the deletion policy that was previously set up with the RMAN CONFIGURE ARCHIVELOG DELETION POLICY command. The Oracle database will resume the default deletion policy behavior, which is to delete archived redo log files that are backed up or obsolete to make space if disk space in the flash recovery area becomes full.

Using the NONE Clause

Use the NONE clause so that archived redo logs in flash recovery area that were backed up or obsolete as per the RMAN retention policy are eligible for deletion. This is the default configuration. Archived redo log files that are backed up or obsolete are deleted to make space if the disk space in the flash recovery area becomes full.

Examples of the CONFIGURE ARCHIVELOG DELETION POLICY Command

When backups of archived redo log files are taken on the standby database:

1. Issue the following command on the primary database:

   CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON STANDBY;
   

2. Issue the following command on the standby database:

   CONFIGURE ARCHIVELOG DELETION POLICY TO NONE;
   

When backups of archived redo log files are taken on the primary database:

1. Issue the following command on the standby database:

   CONFIGURE ARCHIVELOG DELETION POLICY TO APPLIED ON STANDBY;
   

2. Issue the following command on the primary database:

   CONFIGURE ARCHIVELOG DELETION POLICY TO NONE;
   

Regards
Geek DBA