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The control files in the oracle database are binary files that record the database name, database identifier, database creation time, tablespace information, redo log file history, archive log file location and status information, log sequence number, checkpoint, backup status information and location.

The initial installation of oracle will generate 3 control files by default (3 for oracle under windows and 1 for linux)

Find the physical location of the control file

Show parameter control_files

Sql statement:

Select from v$parameter where name='control_files'

So when does the control file start loading?

Control files are more important, it is recommended to store control files in different partitions and create more than 3 control files; next, we will demonstrate moving control files to different partitions.

Oracle 11g uses spfile to start the database by default, while oracle 9i used to start the database with pfile; the pfile and spfile here refer to parameter files.

Query the database started by the parameter file used by the current library

Select decode (count (), 1 recording spfile`) from v$spparameter where rownum=1 and isspecified = 'TRUE'

Before moving the control file, find the location of the control file of the current library

Use the following command to modify the spfile file information, because the spfile file cannot be modified directly through the operating system command, but pfile can be modified directly.

Alter system set control_files='/u01/app/oracle/oradata/control01.ctl' scope=spfile

Close the database after execution

Shutdown immediate;-- this step is very important. Be sure to stop the library and then copy the control files.

Move the control file to the directory to be modified through the operating system command

Restart the database sqlplus / as sysdba

Startup

Control file moved successfully

Let's show you how to add a control file.

Alter system set control_files='/u01/app/oracle/oradata/control01.ctl','/u01/app/oracle/oradata/orcl/control02.ctl' scope=spfile

Close the database-this step is important. Be sure to stop the library and copy the control file.

Copy an original control file to the established directory

Startup starts the database

Check to see if the database is normal

Next, simulate how to repair a control file corruption.

Delete a control file

Unable to shutdown after deleting the control file

Force database shutdown

Shutdown abort

Copy a usable control file to the corrupted control file directory

Start the database

If all the control files are corrupted. Control files need to be backed up, but control files change from time to time. In the later stage, Brother Chicken continues to study how to continuously ensure the integrity of the control files, of course, if your control files are put in different partitions and all hang up, then you can buy × ×!

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