The backup control file is almost the same as a regular control file. It has some areas in it that are marked such that Oracle recognizes that it’s a backup control file. When a backup control file is used, some form of recovery will be required (typically just involving the use of the archived and online redo logs if the database is otherwise intact).To create the backup control file simply issue the alter database backup controlfile to command, indicating at the end of the command where you want the control file to be created.
For example, if you wanted to create a backup control file after the online backup , you would simply need to issue the following command:
SQL> alter database backup controlfile to ‘c:\backup\orcl\backup2\backup_control.ctl’;
The result is the creation of a backup control file called backup_control.ctl found in the c:\backup\orcl\backup2 directory, as you can see here:
SQL> host dir c:\backup\orcl\backup2\backup_control.ctl
Volume in drive C has no label.
Volume Serial Number is 08DE-E1AB
Directory of c:\backup\orcl\backup2
08/02/2008 03:24 PM 10,174,464 BACKUP_CONTROL.CTL
1 File(s) 10,174,464 bytes
0 Dir(s) 9,930,571,776 bytes free