RE: corrupt datafile

From: Mark W. Farnham <mwf_at_rsiz.com>
Date: Mon, 14 Jun 2004 18:56:28 -0400
Message-ID: <KNEIIDHFLNJDHOOCFCDKCECOEOAA.mwf@rsiz.com>

if that outdated file is really all you've got, then you *might* be able to:

cycle off your current undo and make a new one. (Unless you want it to try to roll back incomplete transactions. I'm not sure whether the _corrupt undo and rollback inits are still operative.)
use od or that cool block dumper Steve Adams uses in his classes to look at the headers
use bp to patch the headers to make the file look current (dump the headers of a few current "good" tablespaces to give you a clue, and/or plead for mercy from someone who knows the block header details intimately ($$$$$ usually can provide mercy).
turn on the event that keeps scanning after hitting corrupt blocks, and turn off block checking
give it a whirl and unload or export a table at a time.

Of course your data will be stale and relational integrity will likely be screwed up unless there really was no action on the tablespace.

So understand that unless that tablespace actually was cold and you get no block errors logged, then your data will not be perfect. Depending on whether you have parallel logical logs (non-Oracle application logs or something like that) from which you can replay the subsequent transactions, you may be able to get most or all of what you need.

Also -- the idea below sounds plausible.

Good luck.

mwf

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Shawn Ferris Sent: Monday, June 14, 2004 6:50 PM
To: oracle-l_at_freelists.org
Subject: Re: corrupt datafile

Hey Terry.. RUN!! ;D -- JK

Is there a chance the datafile was compressed externally with compress or gzip? Maybe decompressing it is all that would be required. I know that I've mistakenly tried recovering a database and missed decompressing a datafile only to have dbv say that the entire file is corrupt.

It's been mentioned that maybe the header is corrupt and maybe that is really the case.. however, I find it hard to believe that an entire file is corrupt.

Just a suggestion,

Shawn
Sr. Oracle DBA

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Received on Mon Jun 14 2004 - 17:59:25 CDT