重建控制文件ORA-12720

重建过程出错：
ORA-01503: CREATE CONTROLFILE failed
ORA-12720: operation requires database is in EXCLUSIVE mode
解决办法是停掉一个实例orcl2，然后在orcl1上执行：
sqlplus /nolog
conn sys as sysdba
alter system set cluster_database=FALSE scope=spfile sid='*';
shutdown immediate
可以继续执行重建控制文件的脚本了。

 CREATE CONTROLFILE REUSE DATABASE "ORCL" NORESETLOGS  ARCHIVELOG

    MAXLOGFILES 192

    MAXLOGMEMBERS 3

    MAXDATAFILES 1024

    MAXINSTANCES 32

    MAXLOGHISTORY 292

LOGFILE

  GROUP 1 (

    '+DATA/orcl/onlinelog/group_1.261.831032755',

    '+FRA/orcl/onlinelog/group_1.257.831032791'

  ) SIZE 50M BLOCKSIZE 512,

  GROUP 2 (

    '+DATA/orcl/onlinelog/group_2.262.831032881',

    '+FRA/orcl/onlinelog/group_2.258.831032901'

  ) SIZE 50M BLOCKSIZE 512,

  GROUP 3 (

    '+DATA/orcl/onlinelog/group_3.266.831034657',

    '+FRA/orcl/onlinelog/group_3.259.831034683'

  ) SIZE 50M BLOCKSIZE 512,

  GROUP 4 (

    '+DATA/orcl/onlinelog/group_4.267.831034769',

    '+FRA/orcl/onlinelog/group_4.260.831034799'

  ) SIZE 50M BLOCKSIZE 512

-- STANDBY LOGFILE

DATAFILE

  '+DATA/orcl/datafile/system.256.831032007',

  '+DATA/orcl/datafile/sysaux.257.831032021',

  '+DATA/orcl/datafile/undotbs1.258.831032025',

  '+DATA/orcl/datafile/user01.dbf',

  '+DATA/orcl/datafile/example.264.831033075',

  '+DATA/orcl/datafile/undotbs2.265.831034283',

  '+DATA/orcl/datafile/sicca.270.835217381'

CHARACTER SET AL32UTF8

;

以上脚本是在所有归档日志和在线日志全部存在的情况下执行。控制文件能够从当前的日志文件获取准确的scn和时间点。同样也可以从数据文件中获取准确的scn。