Online backup of a Control File

Yes you could take a online backup of a control file.

SQL> alter database backup controlfile to trace;

This will create a text copy of your controlfile. You could use this text file to recreate your controlfile.

ALTER DATABASE CONTROLFILE TO 'Filename';
Or
ALTER DATABASE CONTROLFILE TO TRACE;

Dear,

      Control file is the backbone of the Oracle Database. It stores structure of the database. Some of the information stored by Control file includes:

1) Startup and shutdown of the database.
2) Log switch and checkpoing information.
3) Tablespace brought online from offline etc...

     As the first point itself states that control file is used even when Database is shutdown. Loss of info from controlfiles require recovery.


Regards
Dharmendra Jaiswal

Dear Friends,


      alter database backup control file to trace ------------------- creates a script for recreating the controlfile. It doesn't take backup by any means.



Regards
Dharmendra Jaiswal

I agree that backing up control file to trace is useful when we need to recreate the control file. But at the same time Alter database BACKUP controlfile to Trace is a means of taking backup of control file. In the command itslef we use the word BACKUP... :-)

I do not agree with you. Backup controlfile to trace would create just  a Scripts for recreating the controlfile. It does not backup the controlfile even when the word backup is used in the command. Remind you control file is used even when database is shutdown. It stores complete database structure. Hence it could not be backed up while database is open.

Regards
Dharmendra Jaiswal.

Alter database backup controlfile to '/oradump/PROD/ctl-bkp.ctl'
Even though DB is online... we can make online bkp on ctl file.

Alter database backup controlfile to trace as 'Path/control.ctl'

it backs up the control file to the location specified..
Or else
Controlfile online backup can be done by using RMAN
RMAN> backup current controlfile;

>>Alter database backup controlfile to 'PATH/control.ctl';

The above query will backup the controlfile in binary format which is not editable and can be used for restore and recovery...
or

We can use RMAN to backup a current controlfile

RMAN>backup current controlfile;

yes.We can take online backup of control file.

Rman >backup current control file

we can do this by suding RMAN:
configure control file auto backup on;

Code
SQL> ALTER DATABASE backup controlfile TO trace AS <PATH> 

Specify the path where you want to store the controlfile backup.