首先要先定位磁盘问题，怀疑到是过期备份导致的。

df -h | awk '$5 >= 90||$4>=90 {print}'
Filesystem            Size  Used Avail Use% Mounted on
                      1.4T  1.3T  115G  92% /d01_test2
                       15G   15G  373M  98% /u01_test1
                       12G   12G  545M  96% /u01_test2


然后切换合适的ORACLE_SID之后，我们开始RMAN操作

rman target /
Configure retention policy to redundancy 1;--指保留一次备份，其余的都是过期的 
--Configure retention policy to recovery window of 7 days;--指保留7天内的备份，其余的都是过期的
RMAN> report obsolete;
RMAN retention policy will 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           97     11-MAY-2013 00:25:40
  Backup Piece       101    11-MAY-2013 00:25:40 /ora_daily2/xxx_041013211003_g3o6oo7o_3_1.rmn
Backup Set           97     11-MAY-2013 00:25:39
  Backup Piece       99     11-MAY-2013 00:25:39 /ora_daily2/xxx_041013211003_g3o6oo7o_2_1.rmn
Backup Set           97     11-MAY-2013 00:25:32
  Backup Piece       75     11-MAY-2013 00:25:32 /ora_daily2/xxx_041013211003_g3o6oo7o_1_1.rmn
Backup Set           98     11-MAY-2013 00:25:41
  Backup Piece       103    11-MAY-2013 00:25:41 /ora_daily2/xxx_041013211003_g4o6oo7q_3_1.rmn
Backup Set           98     11-MAY-2013 00:25:40
  Backup Piece       100    11-MAY-2013 00:25:40 /ora_daily2/xxx_041013211003_g4o6oo7q_2_1.rmn
Backup Set           98     11-MAY-2013 00:25:39
  Backup Piece       98     11-MAY-2013 00:25:39 /ora_daily2/xxx_041013211003_g4o6oo7q_1_1.rmn
Backup Set           111    11-MAY-2013 00:25:44
  Backup Piece       116    11-MAY-2013 00:25:44 /ora_daily2/xxx_041013211003_g9o6pm32_1_1.rmn
Backup Set           112    11-MAY-2013 00:25:45
        
delete obsolete;--就会删除过期备份


下面还可以检查下归档日志

crosscheck archivelog all;--检查过期归档日志
delete expired archivelog all;--删除过期归档日志