RE: FW: backing up rman catalog for disaster recovery

  • From: "Marquez, Chris" <cmarquez@xxxxxxxxxxxxxxxx>
  • To: <oracledba.williams@xxxxxxxxx>, <rgramolini@xxxxxxxxxxxxxxx>
  • Date: Wed, 25 May 2005 21:38:04 -0400

>>I just cheated and backed up the control file separately
"Cheat" nothing this is just smart...or reality :o|

>> run {allocate channel c4 type disk; copy current controlfile to...
>> in my shell script *every* time and AT THE END OF EACH BACKUP
>> NOT an RMAN *backup* of my controlfile (totally useless), 
>> but rather a *COPY* of my controlfile.  
>> Meaning it can be used without RMAN;

As I said in an earlier post, RMAN backup controlfile (IMHO) is rather useless.
It is the classic "chicken and egg".
You have a controlfile in the RMAN backup, but you need a current controlfile 
to get to the backup! (in the absence of a recover catalog).  If I have a 
current controlfile then why do I need the one *in* the backup? 

Oracle should update the RMAN documentation it indicate thsi mental puzzle.

Seems everyone learns this the hard way during testing...or the really hard way 
during a disaster.

Anyone want to guess...
What would be of some use when all current controlfiles and datafiles are lost 
and you have >1 good RMAN backups? (A worst case senario).

Chris Marquez
Oracle DBA

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx on behalf of Dennis Williams
Sent: Wed 5/25/2005 6:15 PM
To: rgramolini@xxxxxxxxxxxxxxx
Cc: oracle-l
Subject: Re: FW: backing up rman catalog for disaster recovery
Actually, RMAN always writes to the control file before it updates the
catalog. So even if you do an RMAN backup using a catalog, you can
still recover the database using only the controlfile. Now, in
Oracle8i I had problems recovering the control file from the RMAN
backup, so I just cheated and backed up the control file separately
after the RMAN backup completed, and made sure the control file backup
was on the same tape as the RMAN backup. I have performed many
recoveries using this method.

Dennis Williams

On 5/25/05, Ruth Gramolini <rgramolini@xxxxxxxxxxxxxxx> wrote:
> One very easy way is to do an rman backup with the nocatalog option.  Thi=
> will use controlfile info for restores and recoveries.  You can use all t=
> options of rman, just no catalog.  That is what we do.
> Just my $0.02,
> Ruth
> -----Original Message-----
> From: Paula_Stankus@xxxxxxxxxxxxxxx
> [mailto:Paula_Stankus@xxxxxxxxxxxxxxx]
> Sent: Wednesday, May 25, 2005 4:49 AM
> To: Paula_Stankus@xxxxxxxxxxxxxxx; rgramolini@xxxxxxxxxxxxxxx;
> all_about_oracle@xxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
> Subject: RE: backing up rman catalog for disaster recovery
> I am setting up a disaster recovery site and I was thinking about the
> best way to do this.
> My theory is that I would like to not just use another recovery catalog
> on the DR site to backup my primary catalog but to somehow keep these
> catalogs constantly in-synch so when I do need to do complete recovery
> and only have the secondary rman catalog available - I wouldn't have to
> recover the catalog as all of the previous backups would be found there.
> So....should I do this using Oracle Data Guard on my disaster recovery
> site catalog or backup rman then restore as my first procedure?  Any
> advice?
> --


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