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RE: Corruption in SYSTEM Tablespace

From: Koivu, Lisa <>
Date: Mon, 29 Oct 2001 11:08:56 -0800
Message-ID: <>

Hi Jeremiah,

Wish it was always that easy.  Last corruption I experienced, we could not chase down the reason for the corruption.  Oracle wanted so many trace files, dumps, etc. lots of info before they would even look at it.  End result, I fixed the problem but I had so much to do (read: tons of code to write) we had to just hope it wouldn't happen again.  We got lucky and for the duration of my employment, it didn't happen a second time.

Have you been able to determine the exact reason for corruption before?

Lisa Koivu
Oracle Database Monkey
Fairfield Resorts, Inc.

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

From:   Jeremiah Wilton []
Sent:   Monday, October 29, 2001 1:15 PM
To:     Multiple recipients of list ORACLE-L
Subject:        RE: Corruption in SYSTEM Tablespace

On Mon, 29 Oct 2001, Gogala, Mladen wrote:

> Restore the last hot backup and do the database recovery.

Well that seems a little extreme.

Why not find out which objects contain corruptions first, and if the corrupted areas actually contain data?  Why go through a restore/recover without having all the information?

Use dba_extents to find out which objects the corrupted blocks belong to.  If they are indexes, just rebuild them!  If they are heap-organized segments (tables/clusters), then find out if there are actually rows in the affected area, by selecting a range of rowids using dbms_rowid.

Only if you find that the corruptions have damaged actual data do you have to recover.  Even in that case, as long as you are using archivelog mode, you can resotre and recover just the datafile(s) containing the corruptions, and perform complete recovery of that file(s) with the database in mount mode.

Finally, make sure you find out how the corruption happened.  The O/S shouldn't just corrupt your database.  The SAs should identify the root cause and rectify it.

Jeremiah Wilton

> > -----Original Message-----
> > From: Rajesh Dayal []
> >
> > Fortunately this is there only in my TEST database. But I am
> > wondering, how to resolve if this happens in Production Database.
> >     I can't export Full database with zero errors. Although I can
> > export most of the schemas individually. Dbverify shows some 3 blocks
> > to be corrupted, that's too only in SYSTEM TS.
> > Any ideas would be appreciated.
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Received on Mon Oct 29 2001 - 13:08:56 CST

Original text of this message