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RE: RMAN disaster recovery

From: Orr, Steve <>
Date: Fri, 30 Nov 2001 16:19:25 -0800
Message-ID: <>

> SYSTEM DOESN'T HAVE THAT DEVICE. Do I simply create a link and RMAN
> will be fine with that?

I vaguely recall that prior versions of the docs did not support this but now I see no such "non-support warning" from Oracle (in the 817 docs) so symbolic links "should" be fine as long as you ensure that they resolve to the same name as occurs in the control files. Quoting page 10-123 of the manual:

"If datafile filenames are symbolic links, that is, files that point to other files, then the control file contains the filenames of the link files but RMAN performs I/O on the datafiles pointed to by the link files. If a link file is lost and you restore a datafile without first re-creating the symbolic link, however, then RMAN restores the datafile to the location of the link file rather than to the location pointed to by the link."

Of course you should test this... and let us know how it turns out. :-)

If you have trouble with the symbolic links then you can always fall back to the "Oracle sanctioned" method Tom pointed out. It's in the section titled, "Moving the Target Database to a New Host with a Different File System," page 6-7. I did this using control files (nocatalog) and it worked just fine.

For comfort factor, I'd recommend that you create the smallest test database you can and prove the 11 steps in this section by restoring your small test DB to another machine. Besides, it's a fun thing to do. :-)

Steve Orr
Bozeman, MT

Speaking of "backups," I got my OOW badge and I'm leaving Walt here to hold down the fort. Between the two of us we've somehow fooled damagement into thinking that they really need us... but the down side is that we can't both be out of town at the same time. So when Walt goes to IOUG I have to stay here as his backup. If you have any more questions about RMAN for the next week feel free to pummel Walt. Along with other folks on this list, he's one of the gurus listed in the Acknowledgments of the new "Oracle RMAN Pocket Reference" from O'Reilly. :-)

-----Original Message-----
Sent: Friday, November 30, 2001 2:05 PM
To: Multiple recipients of list ORACLE-L

Thanks for the input, Cherie, Kimberly, Tom

The part I'm still uncertain is as follows - see the sentence in caps below:

        On my current system let's say I have RMAN write its backup file to a disk location "/ora01". I also have my RMAN catalog on a separate server, and have written an export to my backup tape also.

        After my disaster, my hardware vendor offers me the use of a comparable system at a different location. I grab my backup tape and get in the car. And if it is a real disaster, maybe it is the older backup out of the off-site vault.

        Let's assume that Oracle is already installed on this new system just to move the story along as Hollywood would say.

        I load my RMAN catalog.
SYSTEM DOESN'T HAVE THAT DEVICE. Do I simply create a link and RMAN will be fine with that?

        I fire up RMAN and start the recovery process. Using the syntax Tom provided, I should be able to account for any other device naming or path naming problems.

Kimberly - we aren't quite talking about the need for a standby database. This manager's point, and I feel it is a good one, is that if you have been making backups and storing them off-site, you should be able to mount those backups on a new machine and get your system back. Eventually. Given a lot of time. If something catastrophic happens and you say that because the company didn't spend the big bucks for a duplicate remote data center with a standby database, the recovery will take a week, that would be survivable. But if you say that because you switched to this really keen backup method there is just no way to ever get the data back, well you better make sure your resume was off-site as well.

        Naturally before we quit making weekly cold backups we are going to have to actually test this scenario. I assume that the same applies to your sites also.

Dennis Williams
Lifetouch, Inc.

-----Original Message-----
Sent: Friday, November 30, 2001 11:52 AM To: Multiple recipients of list ORACLE-L

Also, if that is the type of recovery he wants then sell him on a standby database. If you lose your server that severely you will only be able to get back to the last backup regardless of where your recovery catalog is (hopefully on another server or at least backed up).

-----Original Message-----
Sent: Friday, November 30, 2001 7:11 AM
To: Multiple recipients of list ORACLE-L

I have never tried to burn my servers to ash, but I usually try to put the rman catalog on a different server than the ones that it is backing up. You also need to backup the catalog, which I do w/ a nightly export.

>To: Multiple recipients of list ORACLE-L <>
>Subject: RMAN disaster recovery
>Date: Fri, 30 Nov 2001 06:25:23 -0800
>I am wondering how RMAN would work for disaster recovery. Our manager's
>statement is "assume your server is reduced to a pile of ash. Now take your
>backup tape and build me a new system on a loaner from the vendor." I am
>trying to figure how that would work with RMAN. We are still at the stage
>just using RMAN to create disk copies, and we are on Compaq Tru64 UNIX. He
>wants us to demonstrate that level of recoverability, but I'm not sure how
>that would work. I think we could assume that we have a database to load
>the RMAN catalog from an export.
> One issue would be whether the disk location of the RMAN files might
>be different, and I'm not sure how to get RMAN to accept a different
>location. A more minor issue is if the database file locations are
>different, but I think that is pretty well documented.
> Has anyone else tried this? What am I overlooking? Any ideas will be
>Dennis Williams
>Lifetouch, Inc.

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Author: Orr, Steve

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Received on Fri Nov 30 2001 - 18:19:25 CST

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