控制文件(control file)是一個相當小的文件(最多能增長到64M左右),其中包含Oracle需要的其他文件的一個目錄。參數文件告知實例控制文件的位置,控制文件則告知示例數據庫和在線重做日志文件的位置。控制文件還告知了Oracle其他一些事情,如已發生檢查點的有關信息、數據庫名(必須和db_name參數匹配)、創建數據庫的時間戳、歸檔重做日志的歷史(有時這會讓控制文件變大)、RMAN信息等。
控制文件應該通過硬件(RAID)多路保存,如果不支持鏡像,則要通過Oracle多路保存。應該有不止一個副本,而且它們應該保存在不同的磁盤上,以防止萬一出現磁盤故障而丟失控制文件。丟失控制文件並不是致命的,但是會使恢復變得困難很多。
如果丟失了所有的控制文件並且沒有任何的備份,我們可以通過重建控制文件來打開數據庫。其中,重建控制文件至少需要以下信息:
1.數據庫名
2.字符集
3.數據文件名稱
4.初始化參數,包括MAXLOGFILES、MAXLOGMEMBERS、MAXDATAFILES、MAXINSTANCES、MAXLOGHISTORY等;
1.環境准備
數據庫版本
我們在Oracle11g中進行測試。
- SQL>
- SQL> select * from v$version;
- BANNER
- --------------------------------------------------------------------------------
- Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production
- PL/SQL Release 11.2.0.3.0 - Production
- CORE 11.2.0.3.0 Production
- TNS for Linux: Version 11.2.0.3.0 - Production
- NLSRTL Version 11.2.0.3.0 - Production
- SQL>
刪除控制文件
1.通過查詢control_files初始化參數,獲取控制文件路徑;
- SQL>
- SQL> show parameter control_files
- NAME TYPE VALUE
- ------------------------------------ ----------- ------------------------------
- control_files string /u01/app/oracle/oradata/HOEGH/
- control01.ctl, /u01/app/oracle
- /oradata/HOEGH/control02.ctl
- SQL>
2.然后,使用rm命令刪除控制文件;
- [oracle@HOEGH ~]$ rm /u01/app/oracle/oradata/HOEGH/control01.ctl
- [oracle@HOEGH ~]$ rm /u01/app/oracle/oradata/HOEGH/control02.ctl
- [oracle@HOEGH ~]$
3.此時,強制關閉數據庫,然后重啟數據庫,報ORA-00205錯誤。需要注意的是,此時執行shutdown immediate命令,數據庫無法正常關閉,只能關閉到mounted狀態;需要使用shutdown abort命令強制關閉數據庫。
- SQL>
- SQL> shutdown immediate
- Database closed.
- ORA-00210: cannot open the specified control file
- ORA-00202: control file: \'/u01/app/oracle/oradata/HOEGH/control01.ctl\'
- ORA-27041: unable to open file
- Linux Error: 2: No such file or directory
- Additional information: 3
- SQL> select status from v$instance;
- STATUS
- ------------
- MOUNTED
- SQL>
- SQL> shutdown abort
- ORACLE instance shut down.
- SQL>
- SQL>
- SQL> startup
- ORACLE instance started.
- Total System Global Area 941600768 bytes
- Fixed Size 1348860 bytes
- Variable Size 515902212 bytes
- Database Buffers 419430400 bytes
- Redo Buffers 4919296 bytes
- ORA-00205: error in identifying control file, check alert log for more info
- SQL>
2.獲取數據庫名
首先生成文本格式的參數文件;
- SQL>
- SQL> create pfile from spfile;
- File created.
- SQL>
打開參數文件,查看db_name參數值,即為數據庫名稱。
- [oracle@hoegh dbs]$ cat initHOEGH.ora
- HOEGH.__db_cache_size=419430400
- HOEGH.__java_pool_size=4194304
- HOEGH.__large_pool_size=4194304
- HOEGH.__oracle_base=\'/u01/app/oracle\'#ORACLE_BASE set from environment
- HOEGH.__pga_aggregate_target=377487360
- HOEGH.__sga_target=566231040
- HOEGH.__shared_io_pool_size=0
- HOEGH.__shared_pool_size=130023424
- HOEGH.__streams_pool_size=0
- *.audit_file_dest=\'/u01/app/oracle/admin/HOEGH/adump\'
- *.audit_trail=\'db\'
- *.compatible=\'11.2.0.0.0\'
- *.control_files=\'/u01/app/oracle/oradata/HOEGH/control01.ctl\',\'/u01/app/oracle/oradata/HOEGH/control02.ctl\'
- *.db_block_size=8192
- *.db_domain=\'\'
- *.db_name=\'HOEGH\'
- *.diagnostic_dest=\'/u01/app/oracle\'
- *.dispatchers=\'(PROTOCOL=TCP) (SERVICE=HOEGHXDB)\'
- *.memory_max_target=943718400
- *.memory_target=943718400
- *.open_cursors=300
- *.processes=150
- *.remote_login_passwordfile=\'EXCLUSIVE\'
- *.undo_tablespace=\'UNDOTBS1\'
- [oracle@hoegh dbs]$
3.啟動到nomount狀態,獲取字符集
由於需要執行查詢語句select userenv('language') from dual;來獲取字符集,因此需要將數據庫啟動到nomount狀態。
- SQL>
- SQL> startup nomount
- ORACLE instance started.
- Total System Global Area 941600768 bytes
- Fixed Size 1348860 bytes
- Variable Size 515902212 bytes
- Database Buffers 419430400 bytes
- Redo Buffers 4919296 bytes
- SQL>
- SQL> select userenv(\'language\') from dual;
- USERENV(\'LANGUAGE\')
- ----------------------------------------------------
- AMERICAN_AMERICA.US7ASCII
- SQL>
- SQL>
4.獲取數據文件名稱
通過ls命令獲取數據文件列表。
- [oracle@hoegh HOEGH]$ ls -lh
- total 1.8G
- -rw-r----- 1 oracle oinstall 314M May 30 11:07 example01.dbf
- -rw-r----- 1 oracle oinstall 51M May 30 11:07 redo01.log
- -rw-r----- 1 oracle oinstall 51M May 30 11:07 redo02.log
- -rw-r----- 1 oracle oinstall 51M May 30 11:07 redo03.log
- -rw-r----- 1 oracle oinstall 541M May 30 11:07 sysaux01.dbf
- -rw-r----- 1 oracle oinstall 721M May 30 11:07 system01.dbf
- -rw-r----- 1 oracle oinstall 30M Oct 13 2014 temp01.dbf
- -rw-r----- 1 oracle oinstall 96M May 30 11:07 undotbs01.dbf
- -rw-r----- 1 oracle oinstall 5.1M May 30 11:07 users01.dbf
- [oracle@hoegh HOEGH]$
5.生成創建控制文件腳本
這樣,創建控制文件所需的基本信息都已經有了,我們來生成創建控制文件腳本。
- STARTUP NOMOUNT
- CREATE CONTROLFILE REUSE DATABASE \"HOEGH\" NORESETLOGS ARCHIVELOG
- MAXLOGFILES 5
- MAXLOGMEMBERS 3
- MAXDATAFILES 100
- MAXINSTANCES 1
- MAXLOGHISTORY 226
- LOGFILE
- GROUP 1 \'/u01/app/oracle/oradata/HOEGH/redo01.log\' SIZE 50M,
- GROUP 2 \'/u01/app/oracle/oradata/HOEGH/redo02.log\' SIZE 50M,
- GROUP 3 \'/u01/app/oracle/oradata/HOEGH/redo03.log\' SIZE 50M
- DATAFILE
- \'/u01/app/oracle/oradata/HOEGH/system01.dbf\',
- \'/u01/app/oracle/oradata/HOEGH/sysaux01.dbf\',
- \'/u01/app/oracle/oradata/HOEGH/undotbs01.dbf\',
- \'/u01/app/oracle/oradata/HOEGH/users01.dbf\',
- \'/u01/app/oracle/oradata/HOEGH/example01.dbf\',
- \'/u01/app/oracle/oradata/HOEGH/temp01.dbf\'
- CHARACTER SET US7ASCII
- ;
6.重建控制文件
需要注意的是,在執行上述創建腳本時會報錯,系統提示臨時文件不屬於數據文件,如下所示:
- SQL> @/u01/app/oracle/oradata/HOEGH/CreateControlFile.sql
- ORA-01081: cannot start already-running ORACLE - shut it down first
- CREATE CONTROLFILE REUSE DATABASE \"HOEGH\" NORESETLOGS ARCHIVELOG
- *
- ERROR at line 1:
- ORA-01503: CREATE CONTROLFILE failed
- ORA-01160: file is not a data file
- ORA-01110: data file : \'/u01/app/oracle/oradata/HOEGH/temp01.dbf\'
- SQL>
修改腳本並重新執行,重建控制文件后,數據庫會打開到mount狀態。
- SQL>
- SQL> @/u01/app/oracle/oradata/HOEGH/CreateControlFile.sql
- ORACLE instance started.
- Total System Global Area 941600768 bytes
- Fixed Size 1348860 bytes
- Variable Size 515902212 bytes
- Database Buffers 419430400 bytes
- Redo Buffers 4919296 bytes
- Control file created.
- SQL>
- SQL> select status from v$instance;
- STATUS
- ------------
- MOUNTED
- SQL>
7.打開數據庫
在打開數據庫時,會報錯,提示system01數據文件需要執行介質恢復,我們執行recover database即可。
- SQL>
- SQL> alater database open;
- SP2-0734: unknown command beginning \"alater dat...\" - rest of line ignored.
- SQL>
- SQL> alter database open;
- alter database open
- *
- ERROR at line 1:
- ORA-01113: file 1 needs media recovery
- ORA-01110: data file 1: \'/u01/app/oracle/oradata/HOEGH/system01.dbf\'
- SQL>
- SQL> recover database;
- Media recovery complete.
- SQL>
- SQL> alter database open;
- Database altered.
- SQL>
- SQL> select * from v$version;
- BANNER
- --------------------------------------------------------------------------------
- Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production
- PL/SQL Release 11.2.0.3.0 - Production
- CORE 11.2.0.3.0 Production
- TNS for Linux: Version 11.2.0.3.0 - Production
- NLSRTL Version 11.2.0.3.0 - Production
- SQL>
- SQL> select tablespace_name from dba_tablespaces;
TABLESPACE_NAME
------------------------------
SYSTEM
SYSAUX
UNDOTBS1
TEMP
USERS
EXAMPLE
6 rows selected.
SQL>
8.總結
下面總結一下重建控制文件的步驟:
1.獲取數據庫名;
2.獲取字符集名;
3.獲取數據文件名;
4.重建控制文件;
5.執行介質恢復;
6.打開數據庫。