control file multiplexing/Mirroring in oracle
Multiplexing of control file means maintaining more then one control file in different location this is called multiplexing or mirroring of control file. we can maintain minimum 1 maximum 8 Control files.
Example :
Control_files = '/u01/oradata/orcl/control_01.ctl',
'/u02/oradata/orcl/control_02.ctl',
'/u03/oradata/orcl/control_03.ctl'
Steps of Controlfile Multiplexing :-
Step 1:
shutdown the Database
SQL> Shut immediate
Step 2:
Go to the OS Controlfile location and give the command LS
orcl]$ ls
control_01.ctl system.dbf, sysaux.dbf undotbs.dbf userdata.dbf
Copy the current controlfile to another location
orcl]$ cp control_01 /u02/oradata/orcl/control_02.ctl
Step 3:
after finish the copying go to parameter location $ORACLE_HOME/dbs and edit the pfile.
dbs]$ vi initorcl.ora
change controlfile
control_file='/u01.oradata/orcl/control_01.ctl' , '/u02/oradata/orcl/control_02.ctl'
:wq!
Step 4:
after modifying save and quit the pfile and give the command in sqlprompt Startup
SQL> startup
Step 5:
Check the controlfile multiplexed or not
SQL> show parameter control_files
SQL> desc v$controlfile
Recreating control file in oracle
Recreation Of Control file :-
This is the command to Trace and Recreate Controlfile
SQL> ALTER DATABASE BACKUP CONTROLFILE TO TRACE;
you just go to Trace file location UDUMP and give the command like " ls -ltr"
UDUMP]$ ls -ltr
UDUMP]$vi contral_04012012_trace.trc
Your out put modify like this
CREATE CONTROLFILE REUSE DATABASE "ORCL" NORESETLOGS NOARCHIVELOG
MAXLOGFILES 16
MAXLOGMEMBERS 3
MAXDATAFILES 100
MAXINSTANCES 8
MAXLOGHISTORY 292
LOGFILE
GROUP 1 'C:\APP\ORACLE\ORADATA\ORABASE\REDO01.LOG' SIZE 50M,
GROUP 2 'C:\APP\ORACLE\ORADATA\ORABASE\REDO02.LOG' SIZE 50M,
GROUP 3 'C:\APP\ORACLE\ORADATA\ORABASE\REDO03.LOG' SIZE 50M
-- STANDBY LOGFILE
DATAFILE
'C:\APP\ORACLE\ORADATA\ORABASE\SYSTEM01.DBF',
'C:\APP\ORACLE\ORADATA\ORABASE\SYSAUX01.DBF',
'C:\APP\ORACLE\ORADATA\ORABASE\UNDOTBS01.DBF',
'C:\APP\ORACLE\ORADATA\ORABASE\USERS01.DBF',
'C:\APP\ORACLE\ORADATA\ORABASE\EXAMPLE01.DBF',
'C:\APP\ORACLE\ORADATA\ORABASE\UWDATA01.DBF'CHARACTER SET WE8MSWIN1252;
After modifying the script run in nomount state in sql prompt
SQL>startup nomount
SQL>@createcontrlfile.sql
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