在下面的一些情况下，可能需要重建控制文件：
o 所有控制文件都已损坏或丢失
o 没有针对控制文件的备份或者备份已损坏
o 或者在一些情况下，Oracle Support建议这么做
下面是针对RAC环境下重建控制文件的具体过程，包括两个例子。一个是以noresetlogs模式来重建控制文件，一个是以resetlogs模式来重建控制文件。如果redo logs都存在而且没有被损坏，那么可以采用noresetlogs。使用resetlogs会将所有redo log清空而且重置log sequence为1.
在RAC上重建控制文件与单实例有一些小区别：在重建控制文件前必须设置cluster_database=false，而且只启动一个实例来执行操作，否则会报错
ORA-01503: CREATE CONTROLFILE failed
ORA-12720: operation requires database is in EXCLUSIVE mode
重建完控制文件后，需要再将cluster_database设为true.
TESTCASE1
---------------------------
用noresetlog模式重建控制文件
过程：
1.首先生成重建控制文件的脚本：
SQL> alter database backup controlfile to trace;
Database altered.
2. 所生成的控制文件的脚本会在udump下：
SQL> show parameter user_dump_dest
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
user_dump_dest string /u01/app/oracle/diag/rdbms/racdb/RACDB1/trace
数据库的Alert log中也会详细输出这个文件的路径和名字：
alter database backup controlfile to trace
Backup controlfile written to trace file /u01/app/oracle/diag/rdbms/racdb/RACDB1/trace/RACDB1_ora_10076.trc
3. 停止所有数据库实例：
[oracle@rac1 trace]$ srvctl stop database -d RACDB
4. 用noresetlog重建控制文件：
[oracle@rac1 trace]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.3.0 Production on Tue Jan 8 11:23:44 2013
Copyright (c) 1982, 2011, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup nomount; <==启动一个实例
ORACLE instance started.
Total System Global Area 739065856 bytes
Fixed Size 2232032 bytes
Variable Size 549454112 bytes
Database Buffers 184549376 bytes
Redo Buffers 2830336 bytes
SQL> CREATE CONTROLFILE REUSE DATABASE "RACDB" NORESETLOGS ARCHIVELOG
2 MAXLOGFILES 192
3 MAXLOGMEMBERS 3
4 MAXDATAFILES 1024
5 MAXINSTANCES 32
6 MAXLOGHISTORY 292
7 LOGFILE
8 GROUP 1 (
9 '+DATA/racdb/onlinelog/group_1.261.783272805',
10 '+RECO/racdb/onlinelog/group_1.257.783272807'
11 ) SIZE 50M BLOCKSIZE 512,
12 GROUP 2 (
13 '+DATA/racdb/onlinelog/group_2.262.783272807',
14 '+RECO/racdb/onlinelog/group_2.258.783272809'
15 ) SIZE 50M BLOCKSIZE 512,
16 GROUP 3 (
17 '+DATA/racdb/onlinelog/group_3.269.804115405',
18 '+RECO/racdb/onlinelog/group_3.261.804115405'
19 ) SIZE 50M BLOCKSIZE 512,
20 GROUP 4 (
21 '+DATA/racdb/onlinelog/group_4.270.804115405',
22 '+RECO/racdb/onlinelog/group_4.263.804115407'
23 ) SIZE 50M BLOCKSIZE 512
24 -- STANDBY LOGFILE
25 DATAFILE
26 '+DATA/racdb/datafile/system.256.783272707',
27 '+DATA/racdb/datafile/sysaux.257.783272707',
28 '+DATA/racdb/datafile/undotbs1.258.783272707',
29 '+DATA/racdb/datafile/users.259.783272707',
30 '+DATA/racdb/datafile/example.264.783272831',
31 '+DATA/racdb/datafile/undotbs2.265.783273081'
32 CHARACTER SET AL32UTF8
33 ;
CREATE CONTROLFILE REUSE DATABASE "RACDB" NORESETLOGS ARCHIVELOG
*
ERROR at line 1:
ORA-01503: CREATE CONTROLFILE failed
ORA-12720: operation requires database is in EXCLUSIVE mode <============由于没有设置cluster_database=false，所以报错
需要将设置cluster_database=false：
SQL> alter system set cluster_database=false scope=spfile;
System altered.
SQL> shutdown immediate
ORA-01507: database not mounted
ORACLE instance shut down.
SQL> startup nomount;
ORACLE instance started.
Total System Global Area 739065856 bytes
Fixed Size 2232032 bytes
Variable Size 549454112 bytes
Database Buffers 184549376 bytes
Redo Buffers 2830336 bytes
SQL> CREATE CONTROLFILE REUSE DATABASE "RACDB" NORESETLOGS ARCHIVELOG
2 MAXLOGFILES 192
3 MAXLOGMEMBERS 3
4 MAXDATAFILES 1024
5 MAXINSTANCES 32
6 MAXLOGHISTORY 292
7 LOGFILE
8 GROUP 1 (
9 '+DATA/racdb/onlinelog/group_1.261.783272805',
10 '+RECO/racdb/onlinelog/group_1.257.783272807'
11 ) SIZE 50M BLOCKSIZE 512,
12 GROUP 2 (
13 '+DATA/racdb/onlinelog/group_2.262.783272807',
14 '+RECO/racdb/onlinelog/group_2.258.783272809'
15 ) SIZE 50M BLOCKSIZE 512,
16 GROUP 3 (
17 '+DATA/racdb/onlinelog/group_3.269.804115405',
18 '+RECO/racdb/onlinelog/group_3.261.804115405'
19 ) SIZE 50M BLOCKSIZE 512,
20 GROUP 4 (
21 '+DATA/racdb/onlinelog/group_4.270.804115405',
22 '+RECO/racdb/onlinelog/group_4.263.804115407'
23 ) SIZE 50M BLOCKSIZE 512
24 -- STANDBY LOGFILE
25 DATAFILE
26 '+DATA/racdb/datafile/system.256.783272707',
27 '+DATA/racdb/datafile/sysaux.257.783272707',
28 '+DATA/racdb/datafile/undotbs1.258.783272707',
29 '+DATA/racdb/datafile/users.259.783272707',
30 '+DATA/racdb/datafile/example.264.783272831',
31 '+DATA/racdb/datafile/undotbs2.265.783273081'
32 CHARACTER SET AL32UTF8
33 ;
Control file created.
SQL> select * from v$log; <===确认redo log，thread#是正确的
GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC
---------- ---------- ---------- ---------- ---------- ---------- ---
STATUS FIRST_CHANGE# FIRST_TIM NEXT_CHANGE# NEXT_TIME
---------------- ------------- --------- ------------ ---------
1 1 11 52428800 512 2 NO
CURRENT 6876599 08-JAN-13 2.8147E+14
2 1 10 52428800 512 2 NO
INACTIVE 6825446 07-JAN-13 6876599 08-JAN-13
3 2 7 52428800 512 2 NO
INACTIVE 6877338 08-JAN-13 6960724 08-JAN-13
GROUP# THREAD# SEQUENCE# BYTES BLOCKSIZE MEMBERS ARC
---------- ---------- ---------- ---------- ---------- ---------- ---
STATUS FIRST_CHANGE# FIRST_TIM NEXT_CHANGE# NEXT_TIME
---------------- ------------- --------- ------------ ---------
4 2 6 52428800 512 2 NO
INACTIVE 6815353 07-JAN-13 6877338 08-JAN-13
SQL> recover database;
ORA-00283: recovery session canceled due to errors
ORA-00264: no recovery required
SQL> alter system archive log all;
System altered.
SQL> alter database open;
Database altered.
SQL> ALTER TABLESPACE TEMP ADD TEMPFILE '+DATA/racdb/tempfile/temp.263.783272821'
2 SIZE 39845888 REUSE AUTOEXTEND ON NEXT 655360 MAXSIZE 32767M; 《==别忘了添加原来的临时文件到临时表空间中
Tablespace altered.
6.将cluster_database设为true :
SQL> alter system set cluster_database=true scope=spfile;
System altered.
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, Real Application Clusters, OLAP, Data Mining
and Real Application Testing options
7. 启动所有实例：
[oracle@rac1 trace]$ srvctl start database -d RACDB
[oracle@rac1 trace]$ srvctl status database -d RACDB
Instance RACDB1 is running on node rac1
Instance RACDB2 is running on node rac2
TESTCASE2
---------------------------
用resetlogs模式重建控制文件
Test Process:
1.首先生成重建控制文件的脚本：
SQL> alter database backup controlfile to trace;
Database altered.
2. 数据库的Alert log中也会详细输出这个文件的路径和名字：
alter database backup controlfile to trace
Backup controlfile written to trace file /u01/app/oracle/diag/rdbms/racdb/RACDB1/trace/RACDB1_ora_5649.trc
3. 设置cluster_database=false：
SQL> alter system set cluster_database=false scope=spfile;
System altered.
否则，在重建控制文件的时候会报下面的错误：
CREATE CONTROLFILE REUSE DATABASE "RACDB" RESETLOGS ARCHIVELOG
*
ERROR at line 1:
ORA-01503: CREATE CONTROLFILE failed
ORA-12720: operation requires database is in EXCLUSIVE mode
4. 停止所有数据库实例：
[oracle@rac1 trace]$ srvctl stop database -d RACDB
[oracle@rac1 trace]$ srvctl status database -d RACDB
Instance RACDB1 is not running on node rac1
Instance RACDB2 is not running on node rac2
5. 用resetlogs模式重建控制文件：
[oracle@rac1 trace]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.3.0 Production on Tue Jan 8 12:45:25 2013
Copyright (c) 1982, 2011, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup nomount;
ORACLE instance started.
Total System Global Area 739065856 bytes
Fixed Size 2232032 bytes
Variable Size 549454112 bytes
Database Buffers 184549376 bytes
Redo Buffers 2830336 bytes
SQL> CREATE CONTROLFILE REUSE DATABASE "RACDB" RESETLOGS ARCHIVELOG
2 MAXLOGFILES 192
3 MAXLOGMEMBERS 3
4 MAXDATAFILES 1024
5 MAXINSTANCES 32
6 MAXLOGHISTORY 292
7 LOGFILE
8 GROUP 1 (
9 '+DATA/racdb/onlinelog/group_1.261.783272805',
10 '+RECO/racdb/onlinelog/group_1.257.783272807'
11 ) SIZE 50M BLOCKSIZE 512,
12 GROUP 2 (
13 '+DATA/racdb/onlinelog/group_2.262.783272807',
14 '+RECO/racdb/onlinelog/group_2.258.783272809'
15 ) SIZE 50M BLOCKSIZE 512
16 -- STANDBY LOGFILE
17 DATAFILE
18 '+DATA/racdb/datafile/system.256.783272707',
19 '+DATA/racdb/datafile/sysaux.257.783272707',
20 '+DATA/racdb/datafile/undotbs1.258.783272707',
21 '+DATA/racdb/datafile/users.259.783272707',
22 '+DATA/racdb/datafile/example.264.783272831',
23 '+DATA/racdb/datafile/undotbs2.265.783273081'
24 CHARACTER SET AL32UTF8
25 ;
Control file created.
SQL> RECOVER DATABASE USING BACKUP CONTROLFILE UNTIL CANCEL; <=========必须使用UNTIL CANCEL，否则数据库无法open
ORA-00279: change 6976933 generated at 01/08/2013 12:45:12 needed for thread 1
ORA-00289: suggestion : +RECO
ORA-00280: change 6976933 for thread 1 is in sequence #2
Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
CANCEL
Media recovery cancelled.
接下来需要增加其他thread，因为用resetlogs重建controlfile时只是增加了thread为1的redo log：
SQL> ALTER DATABASE ADD LOGFILE THREAD 2
2 GROUP 3 (
3 '+DATA/racdb/onlinelog/group_3.269.804115405',
4 '+RECO/racdb/onlinelog/group_3.261.804115405'
5 ) SIZE 50M BLOCKSIZE 512 REUSE,
6 GROUP 4 (
7 '+DATA/racdb/onlinelog/group_4.270.804115405',
8 '+RECO/racdb/onlinelog/group_4.263.804115407'
9 ) SIZE 50M BLOCKSIZE 512 REUSE;
ALTER DATABASE ADD LOGFILE THREAD 2
*
ERROR at line 1:
ORA-01276: Cannot add file +DATA/racdb/onlinelog/group_3.269.804115405. File
has an Oracle Managed Files file name.
对于ASM，使用了OMF命名规则时不能指定具体的文件名，只需要指定diskgroup名即可：
SQL> ALTER DATABASE ADD LOGFILE THREAD 2
2 GROUP 3 (
3 '+DATA',
4 '+RECO'
5 ) SIZE 50M BLOCKSIZE 512 REUSE,
6 GROUP 4 (
7 '+DATA',
8 '+RECO'
9 ) SIZE 50M BLOCKSIZE 512 REUSE;
Database altered.
SQL> ALTER DATABASE OPEN RESETLOGS;
Database altered.
SQL> ALTER TABLESPACE TEMP ADD TEMPFILE '+DATA/racdb/tempfile/temp.263.783272821'
2 SIZE 39845888 REUSE AUTOEXTEND ON NEXT 655360 MAXSIZE 32767M;
Tablespace altered.
6. 设置cluster_database=true :
SQL> alter system set cluster_database=true scope=spfile;
System altered.
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
7. 启动所有实例：
[oracle@rac1 trace]$ srvctl start database -d RACDB
[oracle@rac1 trace]$ srvctl status database -d RACDB
Instance RACDB1 is running on node rac1
Instance RACDB2 is running on node rac2
在My Oracle Support中有针对重建控制文件的一些说明：
How to Recreate a Controlfile (Doc ID 735106.1)