From: Eric Sandeen Subject: Re: How to recover a damaged ext4 file system? Date: Sat, 07 Feb 2009 13:04:06 -0600 Message-ID: <498DDB26.3080102@redhat.com> References: <20090105135347.GA3337@localdomain> <20090106120527.GT3932@webber.adilger.int> <20090106193404.GA18957@mit.edu> <20090207162725.GA27086@moongate.localnet> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Theodore Tso , Andreas Dilger , linux-ext4@vger.kernel.org To: Christian Ohm Return-path: Received: from mx2.redhat.com ([66.187.237.31]:47067 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752946AbZBGTEe (ORCPT ); Sat, 7 Feb 2009 14:04:34 -0500 In-Reply-To: <20090207162725.GA27086@moongate.localnet> Sender: linux-ext4-owner@vger.kernel.org List-ID: Christian Ohm wrote: > On Tuesday, 6 January 2009 at 14:34, Theodore Tso wrote: >> It looks like both the primary and the backup block group descriptors >> are bad. I'm not sure how this happened; normally nothing touches the >> backup block superblocks at all. Stupid question --- are you sure the >> partition table is sane; that's always the first thing to check. > > I created a new partition on the second drive, and I hope I used exactly the > same options. The result of fdisk -l is the following: > > corrupted drive: > > Disk /dev/sde: 1000.2 GB, 1000204886016 bytes > 255 heads, 63 sectors/track, 121601 cylinders > Units = cylinders of 16065 * 512 = 8225280 bytes > Disk identifier: 0xaaaaaaaa > > Device Boot Start End Blocks Id System > /dev/sde1 1 121601 976760032 83 Linux > > new partition on similar drive: > > Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes > 255 heads, 63 sectors/track, 121601 cylinders > Units = cylinders of 16065 * 512 = 8225280 bytes > Disk identifier: 0xaaaaaaaa > > Device Boot Start End Blocks Id System > /dev/sdb1 1 121601 976760001 83 Linux > > The only difference is the number of blocks of the partition, I guess since the > start and end are the same this should be equal as well. that's counting "cylinders" - try "fdisk -u" to be able to display (or specify) geometry in sectors, which is not a unit open to interpretation... -Eric