From owner-freebsd-hackers@FreeBSD.ORG Tue Apr 15 11:10:35 2014 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id CC917685 for ; Tue, 15 Apr 2014 11:10:35 +0000 (UTC) Received: from mailhost.m5p.com (ip-2-1-0-2.r03.asbnva02.us.ce.gin.ntt.net [IPv6:2001:418:0:5000::16]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 6E5521B4B for ; Tue, 15 Apr 2014 11:10:35 +0000 (UTC) Received: from summer.m5p.com (localhost [IPv6:::1]) by mailhost.m5p.com (8.14.5/8.14.5) with ESMTP id s3FBAQPS043258 for ; Tue, 15 Apr 2014 07:10:31 -0400 (EDT) (envelope-from george+freebsd@m5p.com) Message-ID: <534D13A2.9000706@m5p.com> Date: Tue, 15 Apr 2014 07:10:26 -0400 From: George Mitchell User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: freebsd-hackers@freebsd.org Subject: Clobbered MBR partition table Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.73 on 10.100.0.3 X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.2.7 (mailhost.m5p.com [IPv6:::1]); Tue, 15 Apr 2014 07:10:32 -0400 (EDT) X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Apr 2014 11:10:35 -0000 My laptop has a hard disk I partitioned, whoops, I mean sliced, into four slices when I installed 8.2-STABLE on it a couple of years ago. The first, third, and fourth slices I reserved for future experiments, and most of the space went into the second slice where I installed 8.2-STABLE. Time went on and the second slice is currently running 9.2-STABLE, and I installed 10.0-PRERELEASE on the first slice late last year. But mostly I have been booting off the second slice, which means pressing enter at the initial F1/F2/F3/F4 boot prompt. Then last Friday I was preparing to update the first slice to the latest 10.0-STABLE. Things were going well until I rebooted and typed F1 at the boot prompt. I immediately got a second prompt offering me the options of second disk or PXE. At this point the machine was unbootable, as whatever I typed would cycle between the F1/F2/F3/F4 alternatives and the second disk/PXE alternatives. I hit ctrl-alt-delete and got told there was no bootable disk. So I got a new disk and plugged in into the laptop and started over again. (My first attempt was with a 10.0-RELEASE memstick image, but that's a subject for another day.) Out of conservatism, I have installed 8.4-STABLE on the new disk. Then the first thing I did was to hook up the old disk through a USB adapter and dump it with dd to a backup image. That's going to be finished in a couple of hours, at which point I hope to poke around on the old disk and repair what I assume is a clobbered master boot record partition table. My question is: What's the best tool to help reconstruct the partition table? I think my problem will be mostly solved if I can find the BSD labels on the old disk (which, by the way, has not exhibited any I/O errors during the "dd" backup process). Do BSD labels have a recognizable signature? Thanks for your help and attention. -- George