How To recover lost of all controlfile.

How To recover lost of controlfile,

As a DBA on proactive basis always include controlfile text based backup in every backups.


How to take controlfile text based backup

sql>alter database backup controlfile to trace as 'somepath/bkp_controlfile.txt';



Steps to recover controlfile
        
SQL> STARTUP NOMOUNT
ORACLE instance started.

Total System Global Area  348127232 bytes
Fixed Size                  1248936 bytes
Variable Size             104857944 bytes
Database Buffers          239075328 bytes
Redo Buffers                2945024 bytes
SQL> alter database mount;
alter database mount
*
ERROR at line 1:
ORA-00205: error in identifying control file, check alert log for more info


SQL> CREATE CONTROLFILE REUSE DATABASE "ORCL1" NORESETLOGS  ARCHIVELOG
  2      MAXLOGFILES 16
  3      MAXLOGMEMBERS 3
  4      MAXDATAFILES 100
  5      MAXINSTANCES 8
  6      MAXLOGHISTORY 292
  7  LOGFILE
  8    GROUP 1 'D:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL1\REDO01.LOG'  SIZE 50M,
  9    GROUP 2 'D:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL1\REDO02.LOG'  SIZE 50M,
 10    GROUP 3 'D:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL1\REDO03.LOG'  SIZE 50M
 11  -- STANDBY LOGFILE
 12  DATAFILE
 13    'D:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL1\SYSTEM01.DBF',
 14    'D:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL1\UNDOTBS01.DBF',
 15    'D:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL1\SYSAUX01.DBF',
 16    'D:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL1\USERS01.DBF'
 17  CHARACTER SET WE8MSWIN1252
 18  ;

Control file created.

SQL> alter database open
  2  ;

Database altered.

SQL>