Re: Why control files are needed for restore of hot backup?

Steve wrote:
>
> danielroy10_at_hotmail.com (Daniel Roy) wrote in message news:<1b061893.0205221055.21babbb0_at_posting.google.com>...
> > Would anyone else have an opinion on my issue?
> >
> > Daniel
>
> You can't open your db without your control file(s), period.
> The control file also contains info like the db name, recovery information
> etc. Oracle does not even know where the datafiles are without the control files.

Yes, but I don't think that answers his question. Daniel was asking (if I understood him correctly) whether or not a recreated controlfile (on created using the 'create controlfile' sql command) can suffice for recovery in lieu of a regular current controlfile. The answer is yes. Recreating a controlfile (based on the output of an up-to-date backup controlfile to trace) works as well as a current binary controlfile for just about any common recovery scenario.

In fact, a recreated controlfile has an advantage over restoring an older (non-current) version of a binary controlfile: no need to open resetlogs should you roll past the binary controlfile and completely recover. That's why Oracle's documentation recommends recreating the controlfile vs. restoring an old copy of the controlfile for complete recoveries.

Does that mean you shouldn't multiplex your controlfiles? No, since it's a pain to keep track of all the generated .trc files and hard to guarantee that every structural change is followed by a 'backup controlfile to trace.'

So, Daniel, take hotbackups, backup controlfile to trace when you make structural changes, multiplex your controlfiles (and online redos for that matter), and sleep happy.

Regards,
Sean Received on Thu May 23 2002 - 09:12:57 CDT