RMAN Retention Policy
1. Recovery Window
CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 7 DAYS
SYSDATE - checkpoint_time <= RECOVERY WINDOW
This means, it is possible to discover logical error and fix affected object by point-in-time reovery to just before the error occurs
Always has the number of redundacy of data file backup. A backup can deemed when the more recently backup of the data file has been backup.