Tell me about the obsolete in Rman.

Rman> report obsolete;

RMAN retention policy would be applied to the command
RMAN retention policy is set to redundancy 1
No obsolete backups found

rman> backup DataFile 1;

Starting backup at 29-may-14
Using channel Ora_disk_1
Channel ora_disk_1:starting full datafile backupset
Channel ora_disk_1:specifying DataFile (s) in Backupset
Input datafile fno=00001 name=/u01/app/oracle/oradata/prod/system01.dbf
Channel ora_disk_1:starting piece 1 at 29-may-14
Channel ora_disk_1:finished piece 1 at 29-may-14
Piece Handle=/u01/app/oracle/product/10.2.0/db_1/dbs/amp9g8sf_1_1 tag=tag20140529t102934 Comment=NONE
Channel Ora_disk_1:backup set complete, elapsed time:00:00:25
Finished backup at 29-may-14

Starting Control File and SPFILE autobackup at 29-may-14
Piece handle=/u01/app/oracle/product/10.2.0/db_1/dbs/c-248862348-20140529-00 Comment=none
Finished Control File and SPFILE autobackup at 29-may-14

Rman> list Backup of datafile 1;


List of Backup Sets
===================

BS Key type LV Size Device Type Elapsed Time Completion time
------- ---- -- ---------- ----------- ------------ ---------------
504 Full 391.63M DISK 00:00:23 29-may-14
BP key:504 status:available Compressed:no tag:tag20140529t102934
Piece Name:/u01/app/oracle/product/10.2.0/db_1/dbs/amp9g8sf_1_1
List of datafiles in backup set 504
File LV Type Ckp SCN Ckp time Name
---- -- ---- ---------- --------- ----
1 Full 1588933 29-may-14/u01/app/oracle/oradata/prod/system01.dbf

rman> backup DataFile 1;

Starting backup at 29-may-14
Using channel Ora_disk_1
Channel ora_disk_1:starting full datafile backupset
Channel ora_disk_1:specifying DataFile (s) in Backupset
Input datafile fno=00001 name=/u01/app/oracle/oradata/prod/system01.dbf
Channel ora_disk_1:starting piece 1 at 29-may-14
Channel ora_disk_1:finished piece 1 at 29-may-14
Piece Handle=/u01/app/oracle/product/10.2.0/db_1/dbs/aop9g8u0_1_1 tag=tag20140529t103024 Comment=NONE
Channel Ora_disk_1:backup set complete, elapsed time:00:00:35
Finished backup at 29-may-14

Starting Control File and SPFILE autobackup at 29-may-14
Piece handle=/u01/app/oracle/product/10.2.0/db_1/dbs/c-248862348-20140529-01 Comment=none
Finished Control File and SPFILE autobackup at 29-may-14

Rman> list Backup of datafile 1;


List of Backup Sets
===================

BS Key type LV Size Device Type Elapsed Time Completion time
------- ---- -- ---------- ----------- ------------ ---------------
504 Full 391.63M DISK 00:00:23 29-may-14
BP key:504 status:available Compressed:no tag:tag20140529t102934
Piece Name:/u01/app/oracle/product/10.2.0/db_1/dbs/amp9g8sf_1_1
List of datafiles in backup set 504
File LV Type Ckp SCN Ckp time Name
---- -- ---- ---------- --------- ----
1 Full 1588933 29-may-14/u01/app/oracle/oradata/prod/system01.dbf

BS Key type LV Size Device Type Elapsed Time Completion time
------- ---- -- ---------- ----------- ------------ ---------------
506 Full 391.63M DISK 00:00:27 29-may-14
BP key:506 status:available Compressed:no tag:tag20140529t103024
Piece Name:/u01/app/oracle/product/10.2.0/db_1/dbs/aop9g8u0_1_1
List of Datafiles in backup set 506
File LV Type Ckp SCN Ckp time Name
---- -- ---- ---------- --------- ----
1 Full 1588970 29-may-14/u01/app/oracle/oradata/prod/system01.dbf

Rman> report obsolete;

RMAN retention policy would be applied to the command
RMAN retention policy is set to redundancy 1
Report of obsolete backups and copies
Type Key Completion Time Filename/handle
-------------------- ------ ------------------ --------------------
Backup Set 503 17-mar-14
Backup Piece 503 17-mar-14/u01/app/oracle/product/10.2.0/db_1/dbs/c-248862348-20140317-0b
Backup Set 504 29-may-14
Backup Piece 504 29-may-14/u01/app/oracle/product/10.2.0/db_1/dbs/amp9g8sf_1_1
Backup Set 505 29-may-14
Backup Piece 505 29-may-14/u01/app/oracle/product/10.2.0/db_1/dbs/c-248862348-20140529-00

rman> backup DataFile 1;

Starting backup at 29-may-14
Using channel Ora_disk_1
Channel ora_disk_1:starting full datafile backupset
Channel ora_disk_1:specifying DataFile (s) in Backupset
Input datafile fno=00001 name=/u01/app/oracle/oradata/prod/system01.dbf
Channel ora_disk_1:starting piece 1 at 29-may-14
Channel ora_disk_1:finished piece 1 at 29-may-14
Piece Handle=/u01/app/oracle/product/10.2.0/db_1/dbs/aqp9g90p_1_1 tag=tag20140529t103153 Comment=NONE
Channel Ora_disk_1:backup set complete, elapsed time:00:00:26
Finished backup at 29-may-14

Starting Control File and SPFILE autobackup at 29-may-14
Piece handle=/u01/app/oracle/product/10.2.0/db_1/dbs/c-248862348-20140529-02 Comment=none
Finished Control File and SPFILE autobackup at 29-may-14

Rman> report obsolete;

RMAN retention policy would be applied to the command
RMAN retention policy is set to redundancy 1
Report of obsolete backups and copies
Type Key Completion Time Filename/handle
-------------------- ------ ------------------ --------------------
Backup Set 503 17-mar-14
Backup Piece 503 17-mar-14/u01/app/oracle/product/10.2.0/db_1/dbs/c-248862348-20140317-0b
Backup Set 504 29-may-14
Backup Piece 504 29-may-14/u01/app/oracle/product/10.2.0/db_1/dbs/amp9g8sf_1_1
Backup Set 505 29-may-14
Backup Piece 505 29-may-14/u01/app/oracle/product/10.2.0/db_1/dbs/c-248862348-20140529-00
Backup Set 506 29-may-14
Backup Piece 506 29-may-14/u01/app/oracle/product/10.2.0/db_1/dbs/aop9g8u0_1_1
Backup Set 507 29-may-14
Backup Piece 507 29-may-14/u01/app/oracle/product/10.2.0/db_1/dbs/c-248862348-20140529-01

Tell me about the obsolete in Rman.