12.You performed the RMAN database backup having a backupset key number 231 with the KEEP
FOREVER option.
After some days, you want to change the status of the database backup and you issued the following
command:
RMAN>CHANGE BACKUPSET 231 NOKEEP;
What is the implication of this command?
A. The backup is deleted.
B. The backup is marked unavailable.
C. The backup overrides the backup retention policy.
D. the backup becomes eligible for deletion according to the existing retention policy
Answer: D
解析:
[oracle@demo ~]$ rman target sys/oracle@redhat catalog vpc1/vpc1@catdb;
RMAN> backup tablespace users format "/oradata/backup/tbs_users_%U" keep forever tag tbs_user;
RMAN> list backupset 1311;
List of Backup Sets
===================
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
1311 Full 9.61M DISK 00:00:03 24-NOV-13
BP Key: 1313 Status: AVAILABLE Compressed: NO Tag: TBS_USER
Piece Name: /oradata/backup/tbs_users_0popnh4g_1_1
Keep: BACKUP_LOGS Until: FOREVER
Control File Included: Ckp SCN: 1329314 Ckp time: 24-NOV-13

RMAN> change backupset 1311 nokeep;
RMAN> list backupset 1311;
List of Backup Sets
===================
BS Key Type LV Size Device Type Elapsed Time Completion Time
------- ---- -- ---------- ----------- ------------ ---------------
1311 Full 9.61M DISK 00:00:03 24-NOV-13
BP Key: 1313 Status: AVAILABLE Compressed: NO Tag: TBS_USER
Piece Name: /oradata/backup/tbs_users_0popnh4g_1_1
Control File Included: Ckp SCN: 1329314 Ckp time: 24-NOV-13

参考:http://docs.oracle.com/cd/E11882_01/backup.112/e10642/rcmmaint.htm#BRADV290