From owner-freebsd-questions@FreeBSD.ORG  Wed Nov  8 07:39:20 2006
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
X-Original-To: freebsd-questions@freebsd.org
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 4B1E916A412
	for <freebsd-questions@freebsd.org>;
	Wed,  8 Nov 2006 07:39:20 +0000 (UTC)
	(envelope-from etc@fluffles.net)
Received: from auriate.fluffles.net (a83-68-3-169.adsl.cistron.nl
	[83.68.3.169]) by mx1.FreeBSD.org (Postfix) with ESMTP id E62EE43D45
	for <freebsd-questions@freebsd.org>;
	Wed,  8 Nov 2006 07:39:19 +0000 (GMT)
	(envelope-from etc@fluffles.net)
Received: from destiny ([10.0.0.21])
	by auriate.fluffles.net with esmtpa (Exim 4.63 (FreeBSD))
	(envelope-from <etc@fluffles.net>)
	id 1Ghi1m-0001uv-IJ; Wed, 08 Nov 2006 08:39:18 +0100
Message-ID: <455189B4.7040909@fluffles.net>
Date: Wed, 08 Nov 2006 08:39:32 +0100
From: Fluffles <etc@fluffles.net>
User-Agent: Thunderbird 1.5.0.7 (X11/20060917)
MIME-Version: 1.0
To: illoai@gmail.com
Content-Type: text/plain; charset=ISO-8859-15
Content-Transfer-Encoding: 7bit
Cc: freebsd-questions@freebsd.org
Subject: Re: Reading crashed SCSI disk
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 08 Nov 2006 07:39:20 -0000

>
> I tried
>
> dd if=/dev/da0s1 of=/somefile
>
> dd stopped after a short while with I/O error, after a number of SCSI
> reading errors.
>
> best regards,
>
> Olivier

Hi Olivier,

You might want to try:

dd if=/dev/da0s1 of=/somefile bs=512 options=sync,noerror

The bs=512 means it will transfer sectors (of 512 bytes), this is the
smallest 'units' harddrives are working with. The options=sync,noerror
means that it will continue reading even after bad blocks have been
found. The sync option will cause DD to write zero's in place where it
couldn't read the data. So this command will recover anything that can
be recovered. But, dd will only try once to read the data. Subsequent
tries might succeed while a first try might fail.

If your data is important enough, consider using SpinRite (see
www.grc.com) or some other utility which can actively recover
physical-damaged sectors. I've had good results with SpinRite.

Good luck!

- Veronica