Re: dbv - Found block already marked corrupted
- From: "Kaing, Leng" <Leng.Kaing@xxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 2 Feb 2004 12:54:36 +1100
Mladen,
You're of course right again! I've done all I can - rebuilt the index, =
dropped the index, created the index, yet the block is still reported as =
already marked corrupted. And this time when I do a cdba it points to an =
empty block. Why isn't there a utility to unmark an empty block that was =
previoiusly "marked corrupted"!
I've almost lost faith in this utility now (or maybe I already have!) =
We've just scheduled a weekly job to do a dbv to detect coruption. Now =
I'm getting tons of blocks marked corrupted even though they're clean =
(I know because we do a drop and import from production every night!) It =
would take me forever to make a list and say "if this block for this =
database comes up, ignore it" ARGH!!!
Yes, I'm waiting for the unflag utility too.=20
Leng.
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Date: Fri, 30 Jan 2004 16:02:41 -0500
From: Mladen Gogala <mladen@xxxxxxxxxxxxxxx>
Subject: Re: dbv - Found block already marked corrupted
On 01/30/2004 03:46:04 PM, Tim Gorman wrote:
> One further question, though...
>=20
> >> Of course, if someone knows a utility to un-flag a block I'm all
> ears.
>=20
> Why would anyone want to "unflag" a block that has been flagged as
> corrupt?
> I'm all ears for that... :-)
>=20
> -Tim
Actually, not all corrupt blocks are the same. The definition of a =20
corrupt block is "a block with a bad checksum". These bad checksums are
mostly caused by software. I have a ton of experience with "corrupt =20
blocks" which came into being after copying production database to =20
development database using BCVs. This means hot backup and instance =20
recovery. For the reasons of speed, the tables with the computed data =20
were created with "NOLOGGING" attribute and when access was attempted =20
in the cloned instance, oracle started screaming about "corrupted =20
blocks". When the table was truncated and the data computed again, the =
"corruption" was gone. In other words, so called "corrupt blocks" can
simply be flagged "honest" and reused, if they're empty.
----------------------------------------------------------
Leng Kaing
Email: leng.kaing@xxxxxxxxxxxxxxxx
Phone: +61-3-9203-7589
Mobile: +61-417-371-348
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