From owner-freebsd-hackers  Fri May 26  3:10:40 2000
Delivered-To: freebsd-hackers@freebsd.org
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	id A394937B544; Fri, 26 May 2000 03:10:38 -0700 (PDT)
To: hackers@freebsd.org
Subject: Dell-7500 + Atapi CD-R wierdness
Cc: msmith@freebsd.org, sos@freebsd.org
Message-Id: <20000526101038.A394937B544@hub.freebsd.org>
Date: Fri, 26 May 2000 03:10:38 -0700 (PDT)
From: julian@FreeBSD.ORG (Julian Elischer)
Sender: owner-freebsd-hackers@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG

I have an atapi CD-R drive in my laptop.
under windows I created a disk, using the Adaptec CD-DIRECT 
software. (UDF-1.50)

now I'm using it as a sample of a UDF 1.50 filesystem fo my UDF
code.
however I've hit something rather puzzling:

if I do
dd if=/dev/acd0c of=stuff
and analyse that file,
I get different results than if I access the drive directly.
in a similar vein, when I randomly access block 108362,
I get block 108362, but when I access the disk sequentially,
I find that data at block 108366, 4 blocks away.
Does anyone have any clues?
Specifically I've heard stories of CDrom devices having
very 'approximate' seeking, but this is a bit much,
and I thought that was only when in audio mode..

-- 
      __--_|\  Julian Elischer
     /       \ julian@elischer.org
    (   OZ    ) World tour 2000
---> X_.---._/  presently in:  Perth
            v


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