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RE: dbv - Found block already marked corrupted

From: <babette.turnerunderwood_at_hrdc-drhc.gc.ca>
Date: Mon, 2 Feb 2004 13:52:43 -0500
Message-ID: <FCF2E0B5B7A9CC4EAAD504CE0D2BB5B365D9E9@NCEV02.hrdc-drhc.net>


Yes but Tanel, you're a true geek
For the rest of us mere mortals,=20
if it is not "password" or "bbed" we will NEVER get it ;-)

One of these decades I will get around to using bbed to corrupt my=20 DBA_DEV DB files.

-----Original Message-----
From: oracle-l-bounce_at_freelists.org =
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Tanel Poder Sent: 2004-02-02 1:42 PM
To: oracle-l_at_freelists.org
Subject: Re: dbv - Found block already marked corrupted

Hi!

It's not hard to figure out the password btw - it took 2 minutes from me with a simple script ;)

But bbed should be left alone, unless you're just experimenting for fun = in a
test database...

Tanel.

> Actually, bbed is quite well documented at Rama Velpuri's place.
> The utility itself, is, however, password protected. If you want
> to read more about that oracle hacking utility, go to:
>
> http://www.fors.com/velpuri2/Oracle%20block%20structure/BBED
>
> I tried obtaining the password, to no avail. It is quite well
> protected, and with a reason. This utility makes it possible to
> edit database blocks directly. I would never want to use DUL or
> BBED if I don't really, really have to.
>
>
>
> On 02/02/2004 10:12:42 AM, "Bobak, Mark" wrote:
> > Actually, there is a utility that can do what you want. It's called
> > bbed. But, since it's possible, even easy, to not only shoot
> > yourself
> > in the foot, but actually blow an entire leg off, that's all I'll =
say
> > about it. ;-)
> >
> > -Mark
> >
> > Mark J. Bobak
> > Oracle DBA
> > ProQuest Company
> > Ann Arbor, MI
> > "Imagination was given to man to compensate him for what he is not,
> > and
> > a sense of humor was provided to console him for what he is."
> > --Horace
> > Walpole
> >
> >
> > -----Original Message-----
> > From: Kaing, Leng [mailto:Leng.Kaing_at_team.telstra.com]=3D20
> > Sent: Sunday, February 01, 2004 8:55 PM
> > To: oracle-l_at_freelists.org
> > Subject: Re: dbv - Found block already marked corrupted
> > Importance: High
> >
> >
> > Mladen,
> >
> > You're of course right again! I've done all I can - rebuilt the
> > index,
> > =3D
> > =3D3D
> > dropped the index, created the index, yet the block is still =
reported
> > as
> > =3D3D
> > already marked corrupted. And this time when I do a cdba it points =
to
> > an
> > =3D3D
> > empty block. Why isn't there a utility to unmark an empty block that
> > was
> > =3D3D
> > previoiusly "marked corrupted"!
> >
> > I've almost lost faith in this utility now (or maybe I already =
have!)
> > =3D
> > =3D3D
> > We've just scheduled a weekly job to do a dbv to detect coruption.
> > Now
> > =3D
> > =3D3D
> > I'm getting tons of blocks marked corrupted even though they're =
clean
> > =3D
> > =3D3D
> > (I know because we do a drop and import from production every =
night!)
> > It
> > =3D3D
> > would take me forever to make a list and say "if this block for this
> > =3D3D
> > database comes up, ignore it" ARGH!!!
> >
> > Yes, I'm waiting for the unflag utility too.=3D3D20
> >
> > Leng.
> >
> > ----------------------------------------------------------------
> > Date: Fri, 30 Jan 2004 16:02:41 -0500
> > From: Mladen Gogala <mladen_at_wangtrading.com>
> > Subject: Re: dbv - Found block already marked corrupted
> >
> > On 01/30/2004 03:46:04 PM, Tim Gorman wrote:
> >
> > > One further question, though...
> > >=3D3D20
> > > >> Of course, if someone knows a utility to un-flag a block I'm =
all
> > > ears.
> > >=3D3D20
> > > Why would anyone want to "unflag" a block that has been flagged as
> > > corrupt?
> > > I'm all ears for that... :-)
> > >=3D3D20
> > > -Tim
> >
> >
> > Actually, not all corrupt blocks are the same. The definition of a
> > =3D3D20
> > 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 =
=3D
> > =3D3D20
> > blocks" which came into being after copying production database to
> > =3D3D20
> > development database using BCVs. This means hot backup and instance =
=3D
> > =3D3D20
> > recovery. For the reasons of speed, the tables with the computed =
data
> > =3D3D20
> > were created with "NOLOGGING" attribute and when access was =
attempted
> > =3D3D20
> > in the cloned instance, oracle started screaming about "corrupted
> > =3D3D20
> > blocks". When the table was truncated and the data computed again,
> > the
> > =3D3D
> >
> > "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_at_team.telstra.com
> > Phone: +61-3-9203-7589
> > Mobile: +61-417-371-348
> >
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Received on Mon Feb 02 2004 - 12:52:43 CST

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