From: Christian Ohm Subject: Re: How to recover a damaged ext4 file system? Date: Sat, 7 Feb 2009 17:27:25 +0100 Message-ID: <20090207162725.GA27086@moongate.localnet> References: <20090105135347.GA3337@localdomain> <20090106120527.GT3932@webber.adilger.int> <20090106193404.GA18957@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andreas Dilger , Christian Ohm , linux-ext4@vger.kernel.org To: Theodore Tso Return-path: Received: from mail.gmx.net ([213.165.64.20]:56520 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752291AbZBGQ3q (ORCPT ); Sat, 7 Feb 2009 11:29:46 -0500 Content-Disposition: inline In-Reply-To: <20090106193404.GA18957@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: 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. > Can you upload someplace the output of > > dumpe2fs /dev/XXX > dumpe2fs -o superblock=32768 /dev/XXX > dumpe2fs -o superblock=98304 /dev/XXX > > That would be helpful to see what had happened. Uploaded at http://www.filefactory.com/file/afg88b1/n/dumps_tar_bz2. dump-0 is the output of the first command, dump-32768 the second, and the third was equal to the second. The following two lines weren't redirected into the files (even with 2>&1), and were the same for all three commands (well, at least for the first line that's not really surprising). dumpe2fs 1.41.3 (12-Oct-2008) ext2fs_read_bb_inode: Invalid argument- I couldn't yet compile the findsuper program (some missing headers), but since dumpe2fs found some more or less valid data, it shouldn't be necessary, right? I also tried the R-Linux recovery program mentioned from http://www.data-recovery-software.net/Linux_Recovery.shtml, but that didn't really work (not surprising, since it's for ext3 only). Best regards, Christian Ohm PS: Sorry for the late answer, I'll reply more quickly now.