From owner-freebsd-questions@FreeBSD.ORG Thu Dec 1 02:15:28 2005 Return-Path: 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 7457916A41F for ; Thu, 1 Dec 2005 02:15:28 +0000 (GMT) (envelope-from illusion65@gmail.com) Received: from zproxy.gmail.com (zproxy.gmail.com [64.233.162.196]) by mx1.FreeBSD.org (Postfix) with ESMTP id E437143D49 for ; Thu, 1 Dec 2005 02:15:27 +0000 (GMT) (envelope-from illusion65@gmail.com) Received: by zproxy.gmail.com with SMTP id z6so165101nzd for ; Wed, 30 Nov 2005 18:15:27 -0800 (PST) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:mime-version:content-type; b=ENaVACzBQhM/bj/VEsk0rNAkxxqt46pBJ9ZyrZ2irZ00YKbMEzsAIwG1sYMTYmjxgLyaZrP5wpNxOEv/CatJYvTwPGITgpq0JqtNlhsrAVBRvhx/LBoxptCqPHUhlFysHr3sg4On/Jsx2Y1o8CRiVkOz9a1yKbWjrS3lheBp1e4= Received: by 10.64.196.9 with SMTP id t9mr577050qbf; Wed, 30 Nov 2005 18:15:27 -0800 (PST) Received: by 10.65.233.1 with HTTP; Wed, 30 Nov 2005 18:15:27 -0800 (PST) Message-ID: <57750f110511301815m255cfc23g4688eea38f601e37@mail.gmail.com> Date: Thu, 1 Dec 2005 15:15:27 +1300 From: Doug H To: freebsd-questions@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Subject: Help deriving a corrupted disklabel X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 01 Dec 2005 02:15:28 -0000 One of my disks has 3 active partitions: FreeBSD 5.4-RC3, NTFS (not-bootable), and FreeBSD 6.0-RELEASE. I developed problems while installing FreeBSD 6.0. Installation went as well as can be expected using sysinstall (no difficulty other than pulling packages from the CD), but when I rebooted, nothing was bootable on that disk. I verified that the boot record (using boot0) seems okay: slice tabl= e is fine (40G, 80G, 40G, and 40G unused on 200G drive). Using bsdlabel, I confirmed that slice 3 (FreeBSD 6) is fine, but for some reason I'm not concerned with now, is unbootable. PROBLEM: bsdlabel showed me that slice 1 (FreeBSD 5.4) is damaged and only partition c existed and was incorrect. I do not have / cannot find a written copy of my disklabel for that disk (a good suggestion to *strongly emphasize* in the installation manual for newbies!). I did recall that ad1s1a ('/') was 512M, so I was able to write a label and mount that partition from a "Fixit" shell. QUESTIONS: How can I rederive the remaining disklabel for that disk? Could a copy possibly be stored somewhere on root if I didn't do it myself when building the system? I have not tried to boot from that root partition. Trying several possible labels has resulted in "incorrect super block" errors for the partitions after 'a'. Random guessing will be very tedious. My research has indicated that I could binary grep the raw ad1s1c partition to locate the magic numbers for the super blocks and derive the partitions from that information. I even found a little 'c' language program Peter Dufault posted 11 years ago on this list to locate magic numbers. My hope is that in 11 years of development, FreeBSD would have created a clever tool to aid this process! I've found enough entries in these lists to think that the effort would be justified and much appreciated. If there is no tool, can someone tell me the value of FS_UFS2_MAGIC? I presume that's what I should search for - it's a UFS2 filesystem. Having only a "Fixit" shell is somewhat limiting. Thanks, Doug