Re: coping the control file

"Keth Slaton" <kslaton_at_newsguy.com> wrote in message news:mqontssg1s7siqd6dj7k4t322q0opu3vuk_at_4ax.com...
> Could there ever be a competent newbe question? Oh well
>
> My question is this when working with control files I understand that
> I must use the alter database command to create a human readable text
> file. But would it be possible to just copy the file from one
> directory to another? Oh and would I need to do this durning system
> maintenance or could I copy the file at anytime.
>
> Thanks in advance

If the database is up and running, then no, you can't just copy the control file -it will be internally inconsistent, and unuseable. That's why the command 'alter database backup controlfile to 'c:\overthere\control.bkp' was invented -because Oracle is producing the copy, it is guaranteed consistent. However, that command can indeed be issued at any time of the day or night.

If the database is fully shut down, then you can copy it as though it were any other file on your disk.

But the real issue is this: copying the controlfile is fine for when you want to start out mirroring. After that, binary versions of the controlfile are a royal pain in the butt to work with. When you come to use an old binary copy of the controlfile to recover a database that has lost all its originals, you will be forced to open the database with a resetlogs -and that means, nasically, that all prior backups and all prior archives (if you're taking them) are rendered instantly worthless -they now relate to a prior incarnation of the database, and can't be used for the present incarnation (except under extraordinary circumstances). Resetlogs is, therefore, a VERY expensive option, and a binary image of the controlfile will guarantee one.

The text script you mention (the 'backup controlfile to trace' trace file) is much the preferred method of recovering from total controlfile loss, provided you keep it up to date... using it, all required copies of the controlfile are regenerated from scratch, with the system forcing the highest SCN found amongst the datafiles into the header of the new controlfiles. Thus, there is no resetlogs, and all prior backups and archives remain entirely useable.

Regards
HJR Received on Thu Oct 05 2000 - 19:21:43 CDT