Re: benefits of multiple switch logfile calls?

From: Don Seiler <don_at_seiler.us>
Date: Fri, 05 Dec 2003 16:26:43 GMT
Message-ID: <pan.2003.12.05.16.29.02.882648@seiler.us>

On Fri, 05 Dec 2003 07:58:07 +1100, Howard J. Rogers wrote:

> Any set of instructions that goes to the effort of copying the online logs,
> and then renaming them to point out that the copies should never be used,
> are not "solid". Another 6-letter word beginning with 's' and ending in 'd'
> springs to mind. Not your fault, I realise.

Fair enough and I can easily take those commands out. I realised when analyzing it that those redo log backups could never be used and wondered why the original script author had them in there.

>>
>> Also, Howard, you think that just the ALTER SYSTEM ARCHIVE LOG CURRENT;
>> statement is enough?  Does it matter if we do it before or after backing
>> up the control file to trace?

>
> It makes no difference. The controlfile trace script cheats. It re-creates
> the controlfile empty; it then populates the controlfile with pointers to
> where all the data files and online redo logs are. It then hares off down
> those pointers to read the SCN in the header of each datafile. It takes the
> highest SCN it finds, and writes that into the SCN of the new controlfile.
> It then uses that as the basis for performing recovery. Therefore, it is
> irrelevant when you take the tracefile backup, because the new controlfile
> starts virgin and uses the existing state of the surviving components of the
> database as a way of reconstructing itself.
>

So overall do you think my original problem was due to trying the "using backup controlfile" method rather than re-creating the controlfile from the code in the trace file? Received on Fri Dec 05 2003 - 10:26:43 CST