Re: Backup Controlfile / Recover Database Question

Hi Bill,

Actually a control file is what it says: it has control information . The control information amongst others is the last SCN (system commit number) and the latest redo log sequence. It is used to determine what redo log files (archived or online) you need.
If you wouldn't have used the using backup controlfile (which means: the controlfile is NOT current, it is from a backup) it would have started asking for redo log files.
In this case because you used
a) resetlogs, which did reset the redo log sequence number to 1 (or 0) b) using backup controlfile
recovery didn't make any assumptions and simply read through all what was supplied.
So, you did use the backup controlfile in a sense.

Hth,

Sybrand Bakker, Oracle DBA

Bill Buchan <bill.buchan_at_ossian.net> wrote in message news:7nnbam$q4g$1_at_phys-ma.sol.co.uk...
> I'm looking for help with the purpose of binary controlfile backups. What
> do you use them for?
>
> Specifically, can somebody explain what happened here?
> I was testing a recovery situation where all I had left were the datafiles
> and the archive redo log files (ie. no controlfiles, on-line logs,
password,
> init.ora). The password files and init.ora were easily recreated.
>
> I then wrote a CREATE CONTROLFILE .. RESET LOGS script based on "backup
> controlfile to trace" on a different database and editing it to match the
> datafiles names and directories that I had copied from tape.
>
> Once the instance was up and running again, I entered the command
>
> > ALTER DATABASE RECOVER UNTIL TIME '1999-07-28:10:30:00'; -- before the
> start of the on-line logs
>
> ORA-01610: recovery using the BACKUP CONTROLFILE option must be used
>
> > ALTER DATABASE RECOVER UNTIL TIME '1999-07-28:10:30:00' USING BACKUP
> CONTROLFILE;
>
> ORA-00279: change 493146 generated at 07/28/99 05:00:04 needed for thread
1
> ORA-00289: suggestion: F:\ORADATA\ORCL\ARCHIVE\ORCLT0001S235.ARC
> ORA-00280: change 493146 for thread 1 is in sequence #235
>
> > ALTER DATABASE RECOVER AUTOMATIC CONTINUE;
> > ALTER DATABASE OPEN RESETLOGS;
>
> and the database opened...
>
> At no point did I have or apply a backup controlfile - what is the point
of
> "USING BACKUP CONTROLFILE"? And what is the point of taking a backup
> controlfile if you don't seem to need it?
>
> Any explanations will be gratefully received!
>
> Many thanks,
>
> - Bill.
>
>
>
>
>
Received on Wed Jul 28 1999 - 13:04:30 CDT