Rman retention window doubt

Question

Hello, i have RMAN backup in the way of backupsets on two node 11gR2 RAC on linux standard edition.
RMAN> show all;
using target database control file instead of recovery catalog
RMAN configuration parameters for database with db_unique_name MGW are:
CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 1 DAYS;
CONFIGURE BACKUP OPTIMIZATION OFF; # default
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE MAXSETSIZE TO UNLIMITED; # default
CONFIGURE ENCRYPTION FOR DATABASE OFF; # default
CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default
CONFIGURE COMPRESSION ALGORITHM 'BASIC' AS OF RELEASE 'DEFAULT' OPTIMIZE FOR LOAD TRUE ; # default
CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/u01/app/oracle/product/11.2.0/dbhome_1/dbs/snapcf_mgw2.f'; # default
RMAN>And now i dont understand why RMAN is not deleting backupsets that are older then 24 hours , although i have set
CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 1 DAYS.
I have in my rman script that is executing every day @ 23:00 this:
backup as COMPRESSED BACKUPSET database FORMAT '/home/oracle/rman/%U' plus archivelog delete input;
delete noprompt obsolete;And now i see in my rman backup folder that there is backupset from yesterdey 23:00 ,and also from the day before yesterday 23:00.
[oracle@data02 rman]$ ls -l
total 51889864
-rw-r----- 1 oracle asmadmin 26454474752 Jul 14 00:19 0bmhcc1s_1_1
-rw-r----- 1 oracle asmadmin     1245184 Jul 14 00:19 0cmhcg84_1_1
-rw-r----- 1 oracle asmadmin 26626334720 Jul 15 00:18 0fmhf0ep_1_1
-rw-r----- 1 oracle asmadmin     1245184 Jul 15 00:18 0gmhf4ih_1_1
-rw-r--r-- 1 oracle oinstall           0 Jul 14 16:52 aa_1_1I thoght that if i have run my rman script today @ 23:00 , than that will do backup but also delete backup from the day before because i have set
retention to 1 day .
Can you please say why i am wrong in this ?

Answer 1

The RMAN retention policy doesn't just keep the amount of days specified. It calculates the interval from the end of the current time and extends back in time for the number of days specifed.
So for example if you set the backup retention policy to 1 day today. Then RMAN will keep the backups for 15th July, 16th July.
Then on the 17th July, the 15th July backup will be obsolete.
I.e.
Current date   Status                                 Recovery Point
15th July        available                               15-1 = 14th July
16th July        available                               16-1 = 15th July
17th July        backup of 15th July obsolete  17-1 = 16th July
So your backup for today wouldn't be marked as obsolete until the 17th July.
5 Configuring the RMAN Environment
However, if you have a fixed-date database then you should be setting the retention policy to redundancy instead of recovery window.
RMAN> CONFIGURE RETENTION POLICY TO REDUNDANCY 1;