Oracle UNDO表空间重建与恢复

UNDO表空间的数据文件从OS直接删除了，数据库还没shutduwn，UNDO需要恢复。

1，数据库正常运行状态中；

2，rm - fundotbs02.dbf， 数据库在不知情的情况下接着运行，直到有日志错误告警。

Fri Apr 19 13:27:03 2013
[3942] ORA-01554 reason: failed to get txn-enqueue TX-0x000d0000-0x00000000
Errors in file /u01/app/Oracle/diag/rdbms/ora11g/ORA11G/trace/ORA11G_smon_3942.trc:
ORA-01595: error freeing extent (17) of rollback segment (13))
ORA-01554: transaction concurrency limit reached reason:failed to get TX-enqueue params:851968, 0
Fri Apr 19 13:27:51 2013
Errors in file /u01/app/oracle/diag/rdbms/ora11g/ORA11G/trace/ORA11G_j000_10253.trc:
ORA-12012: error on auto execute of job 43
ORA-01116: error in opening database file 7
ORA-01110: data file 7: '/u01/app/oracle/ORA11G/undotbs02.dbf'
ORA-27041: unable to open file
Linux Error: 2: No such file or directory
Additional information: 3
Errors in file /u01/app/oracle/diag/rdbms/ora11g/ORA11G/trace/ORA11G_j000_10253.trc:
ORA-12012: error on auto execute of job 43
ORA-01116: error in opening database file 7
ORA-01110: data file 7: '/u01/app/oracle/ORA11G/undotbs02.dbf'
ORA-27041: unable to open file
Linux Error: 2: No such file or directory
Additional information: 3

3，此时创建spfile也会报错。
 SQL> create pfile from spfile;
 create pfile from spfile
 *
 ERROR at line 1:
 ORA-01116: error in opening database file 7
 ORA-01110: data file 7: '/u01/app/oracle/ORA11G/undotbs02.dbf'
 ORA-27041: unable to open file
 Linux Error: 2: No such file or directory
 Additional information: 3
 4，此时，注意保留现场，不要随意关闭数据库，查询有哪里UNDO的段正在使用。
 SQL> select * from v$rollname;
        USN NAME
 ---------- ------------------------------
          0 SYSTEM
        11 _SYSSMU11_2087506584$
        12 _SYSSMU12_1903386335$
        13 _SYSSMU13_3816552520$
        14 _SYSSMU14_2728152801$
        15 _SYSSMU15_2082928664$
        16 _SYSSMU16_1938921541$
        17 _SYSSMU17_3062294638$
 
8 rows selected.
 如果数据库已经强行关闭了，可以查询如下。
 SQL> select segment_name,status,tablespace_name from dba_rollback_segs where status='NEEDS RECOVERY';
    SEGMENT_NAME                  STATUS          TABLESPACE_NAME
 ------------------------------ ---------------- ------------------------------
 

        11 _SYSSMU11_2087506584$ NEEDS RECOVERY  UNDOTBS2
        12 _SYSSMU12_1903386335$ NEEDS RECOVERY  UNDOTBS2
        13 _SYSSMU13_3816552520$ NEEDS RECOVERY  UNDOTBS2
        14 _SYSSMU14_2728152801$ NEEDS RECOVERY  UNDOTBS2
        15 _SYSSMU15_2082928664$ NEEDS RECOVERY  UNDOTBS2
        16 _SYSSMU16_1938921541$ NEEDS RECOVERY  UNDOTBS2
        17 _SYSSMU17_3062294638$ NEEDS RECOVERY  UNDOTBS2