From: Drew Reusser Subject: Re: Issue with bad file system Date: Mon, 19 Nov 2012 17:00:59 +0000 Message-ID: References: <20121119083245.18044.qmail@science.horizon.com> <50AA503D.2060503@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: George Spelvin , linux-ext4@vger.kernel.org To: Eric Sandeen Return-path: Received: from mail-la0-f46.google.com ([209.85.215.46]:62105 "EHLO mail-la0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753362Ab2KSRBB (ORCPT ); Mon, 19 Nov 2012 12:01:01 -0500 Received: by mail-la0-f46.google.com with SMTP id p5so1259035lag.19 for ; Mon, 19 Nov 2012 09:00:59 -0800 (PST) In-Reply-To: <50AA503D.2060503@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, Nov 19, 2012 at 3:29 PM, Eric Sandeen wrote: > On 11/19/12 2:32 AM, George Spelvin wrote: > ... > >> "e2fsck -n" will only print errors and not change anything. It's >> always safe. >> >> Try "e2fsck -n -v /dev/md0" (given the dumpe2fs failure, I expect that >> will not work) and then try "e2fsck -n -v -b 32768 /dev/md0". >> >> I don't know what happened to your superblock, but if that's all that >> got trashed, recovery is actually quite straightforward and there's no >> risk of data loss. e2fsck will just print a huge number of "free blocks >> count wrong" messages as it fixes them. >> >> (However, that's a pretty big "if".) >> >> >> Another thing that would be useful is "dd if=/dev/md0 skip=2 count=2 | xxd" >> (or od -x if you don't have xxd). That will give a hex dump of the >> primary superblock, which might show the extent of the damage. >> >> >> If "e2fsck -n -b 32768" works, the way to repair it is to run it again >> without the "-n", but the -n output will say how bad it is. > > Whoops, I replied without seeing these other replies; somehow threading > was broken w/ George's first reply. > > Anyway - I would not go to e2fsck yet. I think your raid is mis-assembled. > I'd investigate that first. I'll look at the other output a bit more, but > for now, I'd stay away from fsck - just wanted to get that out there quick. > > -Eric Can you give me more details as to why you think the raid is misassembled? mint ~ # mdadm --examine /dev/sd[abde]1 /dev/sda1: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : db9e3115:556a49db:27c42d30:02657472 Name : mint:0 (local to host mint) Creation Time : Thu Nov 15 11:08:02 2012 Raid Level : raid10 Raid Devices : 4 Avail Dev Size : 1953259520 (931.39 GiB 1000.07 GB) Array Size : 1952211968 (1861.77 GiB 1999.07 GB) Used Dev Size : 1952211968 (930.89 GiB 999.53 GB) Data Offset : 262144 sectors Super Offset : 8 sectors State : clean Device UUID : 933ec5c0:d6819e33:adb0e6c8:90e337bd Update Time : Thu Nov 15 15:08:55 2012 Checksum : b516984f - correct Events : 17 Layout : near=2 Chunk Size : 512K Device Role : Active device 0 Array State : AAAA ('A' == active, '.' == missing) /dev/sdb1: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : db9e3115:556a49db:27c42d30:02657472 Name : mint:0 (local to host mint) Creation Time : Thu Nov 15 11:08:02 2012 Raid Level : raid10 Raid Devices : 4 Avail Dev Size : 1952212992 (930.89 GiB 999.53 GB) Array Size : 1952211968 (1861.77 GiB 1999.07 GB) Used Dev Size : 1952211968 (930.89 GiB 999.53 GB) Data Offset : 262144 sectors Super Offset : 8 sectors State : clean Device UUID : 9d6df7c7:ce401405:4ea18763:a528ecc5 Update Time : Thu Nov 15 15:08:55 2012 Checksum : 3103c408 - correct Events : 17 Layout : near=2 Chunk Size : 512K Device Role : Active device 1 Array State : AAAA ('A' == active, '.' == missing) /dev/sdd1: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : db9e3115:556a49db:27c42d30:02657472 Name : mint:0 (local to host mint) Creation Time : Thu Nov 15 11:08:02 2012 Raid Level : raid10 Raid Devices : 4 Avail Dev Size : 1953259520 (931.39 GiB 1000.07 GB) Array Size : 1952211968 (1861.77 GiB 1999.07 GB) Used Dev Size : 1952211968 (930.89 GiB 999.53 GB) Data Offset : 262144 sectors Super Offset : 8 sectors State : clean Device UUID : fa1a1b82:989e933a:95e4d249:5cee901d Update Time : Thu Nov 15 15:08:55 2012 Checksum : 5ea6d02d - correct Events : 17 Layout : near=2 Chunk Size : 512K Device Role : Active device 2 Array State : AAAA ('A' == active, '.' == missing) /dev/sde1: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : db9e3115:556a49db:27c42d30:02657472 Name : mint:0 (local to host mint) Creation Time : Thu Nov 15 11:08:02 2012 Raid Level : raid10 Raid Devices : 4 Avail Dev Size : 1952212992 (930.89 GiB 999.53 GB) Array Size : 1952211968 (1861.77 GiB 1999.07 GB) Used Dev Size : 1952211968 (930.89 GiB 999.53 GB) Data Offset : 262144 sectors Super Offset : 8 sectors State : clean Device UUID : 594ed481:471ef11a:027f1c24:6f9d057d Update Time : Thu Nov 15 15:08:55 2012 Checksum : 786bd4bc - correct Events : 17 Layout : near=2 Chunk Size : 512K Device Role : Active device 3 Array State : AAAA ('A' == active, '.' == missing)