From owner-freebsd-hackers Wed Aug 11 9:35:50 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from florence.pavilion.net (florence.pavilion.net [194.242.128.25]) by hub.freebsd.org (Postfix) with ESMTP id 0745815581; Wed, 11 Aug 1999 09:35:44 -0700 (PDT) (envelope-from joe@florence.pavilion.net) Received: (from joe@localhost) by florence.pavilion.net (8.9.3/8.8.8) id RAA16474; Wed, 11 Aug 1999 17:35:35 +0100 (BST) (envelope-from joe) Date: Wed, 11 Aug 1999 17:35:35 +0100 From: Josef Karthauser To: Dag-Erling Smorgrav Cc: hackers@FreeBSD.ORG, fs@FreeBSD.ORG Subject: Re: Disk label recovery - request for suggestions. Message-ID: <19990811173535.Y88035@pavilion.net> References: <19990808185112.A99557@pavilion.net> <19990811171514.X88035@pavilion.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.95.4i In-Reply-To: ; from Dag-Erling Smorgrav on Wed, Aug 11, 1999 at 06:23:24PM +0200 X-NCC-RegID: uk.pavilion Organisation: Pavilion Internet plc, 24 The Old Steine, Brighton, BN1 1EL, England Phone: +44-845-333-5000 Fax: +44-845-333-5001 Mobile: +44-403-596893 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Wed, Aug 11, 1999 at 06:23:24PM +0200, Dag-Erling Smorgrav wrote: > Josef Karthauser writes: > > Ahha - of course. Ok, let me re-phrase the question then. By looking > > at the contents of the superblocks on a UFS file system it's possible to > > reconstruct a disklabel for a slice. > > Well, it's possible to reconstruct the label information for *that > particular UFS file system*, since if you know the location of the > superblock (or one of its backup copies), you can determine the offset > and size of the FS. It won't tell you anything about *other* > partitions though. That's ok, because each slice has its _own_ label. If the bios partition table loses it's mind that's a little more work :). > > Is this trick possible with other kinds of file systems too? > > That's totally dependent on the particular file system. For instance, > a swap partition contains no metadata (that I know of), so all you can > do is deduce it's size and position from the sizes and positions of > surrounding partitions, and of the slice they're in. > What are the implications of adding a metadata structure to the swap structure. (It only needs a block :). [Although thinking out loud, it's complicated because there's no 'newfs' process that touches the partition, on the other hand the size of the partition is known at swap-mounting time, so the meta data could be written at that point.] Joe -- Josef Karthauser FreeBSD: How many times have you booted today? Technical Manager Viagra for your server (http://www.uk.freebsd.org) Pavilion Internet plc. [joe@pavilion.net, joe@uk.freebsd.org, joe@tao.org.uk] To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message