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Date:      Fri, 01 Aug 2003 11:50:46 +0200
From:      Andy Polyakov <appro@fy.chalmers.se>
To:        Chuck Swiger <cswiger@mac.com>
Cc:        stable@freebsd.org
Subject:   Re: [Fwd: dvd+rw-format -force problem]
Message-ID:  <3F2A37F6.DA046CDA@fy.chalmers.se>
References:  <3F298DD2.4070001@mac.com>

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> -------- Original Message --------
> Subject: dvd+rw-format -force problem
> Date: Thu, 31 Jul 2003 21:30:00 +0200
> From: Melvyn Sopacua <freebsd-stable@webteckies.org>
> Organization: WebTeckies.org
> To: stable@freebsd.org
> 
> I haven't felt the need to fully blank a DVD+RW for a while untill today.

Formally speaking blanking is not appicable to DVD+RW. dvd+rw-format
-force merely zeros bitmap which describes which ECC blocks were
de-iced/written to and nullifies few blocks in the beginning of the
media. It's not what one would normally consider as [full] blanking. If
you want to nullify the media, e.g. for privacy reasons, 'dvd+rw-format
-force /dev/cd0c' won't do the tick, 'growisofs -Z /dev/cd0c=/dev/zero'
would.

> The problem is the following:
> When issuing:
> dvd+rw-format -force /dev/cd0c
> 
> it fails, with 'unable to unmount' error.

I see the problem now. Fortunately I'm preparing new update addressing
performance problems with Pioneer DVR-x06 and will incorporate proper
solution even for this problem:-)

> A little tracing in the source, shows that the following patch, will work -

The proposed solution is not appropriate from security viewpoint, but as
already mentioned, proper solution will be provided in the upcoming
update, which will be released shortly. Meanwhile just write over the
old recording in exact same way it was originally performed, namely with
'growisofs -Z /dev/cd0c ...'.

> Can anybody tell wether the author's expectation is wrong,

Yes, my expectations were wrong, it's a bug and well be fixed. Cheers.
A.



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