Configuring Redo Log Retention
By default, archivelog deletion policy is disabled. While the archivelog deletion policy is disabled, RMAN deletes archived redo log backups according to the backup retention policy. If the backup retention policy is not configured, RMAN stores only the latest archived log backup.
To configure archivelog deletion policy, run the following command. When the number of archived log backups exceeds the specified number, RMAN deletes the oldest archived log backup.
CONFIGURE ARCHIVELOG DELETION POLICY TO BACKED UP 3 TIMES TO SBT;
To disable archivelog deletion policy, run the following command:
CONFIGURE ARCHIVELOG DELETION POLICY TO NONE;
For details, see the Configuring the Backup Retention Policy section of the Oracle Database Backup and recovery User's Guide.