From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5983C433C1 for ; Sun, 28 Mar 2021 21:04:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A1BCB61481 for ; Sun, 28 Mar 2021 21:04:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231375AbhC1VD2 (ORCPT ); Sun, 28 Mar 2021 17:03:28 -0400 Received: from smtp.hosts.co.uk ([85.233.160.19]:16644 "EHLO smtp.hosts.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231367AbhC1VC6 (ORCPT ); Sun, 28 Mar 2021 17:02:58 -0400 Received: from host86-155-154-65.range86-155.btcentralplus.com ([86.155.154.65] helo=[192.168.1.64]) by smtp.hosts.co.uk with esmtpa (Exim) (envelope-from ) id 1lQaSV-0004Xg-8Y; Sun, 28 Mar 2021 19:48:24 +0100 Subject: Re: why won't this RAID5 device start? To: David T-G , Linux RAID list References: <20210328021451.GB1415@justpickone.org> From: Wols Lists X-Enigmail-Draft-Status: N1110 Message-ID: <6060D8AA.9030504@youngman.org.uk> Date: Sun, 28 Mar 2021 20:27:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 MIME-Version: 1.0 In-Reply-To: <20210328021451.GB1415@justpickone.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On 28/03/21 03:14, David T-G wrote: > Hi, all -- > > I recently migrated our disk farm to a new box with a new OS build > (openSuSE from KNOPPIX). Aside from the usual challenges of setting > up the world again, I have a 3-device RAID5 volume that won't start. > The other metadevice is fine, though; I think we can say that the md > system is running. Soooooo ... Where do I start? > > diskfarm:~ # cat /proc/mdstat > Personalities : [raid6] [raid5] [raid4] > md0 : active raid5 sdc1[3] sdd1[4] sdb1[0] > 11720265216 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/3] [U_UU] This looks wrong - is this supposed to be a four-drive array? U_UU implies a missing drive ... as does [4/3] > > md127 : inactive sdl2[0](S) sdj2[3](S) sdf2[1](S) > 2196934199 blocks super 1.2 > > unused devices: > > [No, I don't know why md127 was first a moment ago!] I tried reassembling > the device, but mdadm doesn't like it. > > diskfarm:~ # mdadm --stop /dev/md127 > mdadm: stopped /dev/md127 > diskfarm:~ # mdadm --assemble --scan > mdadm: /dev/md/750Graid5md assembled from 1 drive - not enough to start the array. > mdadm: Found some drive for an array that is already active: /dev/md/0 > mdadm: giving up. > mdadm: No arrays found in config file or automatically > > But ... what's with just 1 drive? > > diskfarm:~ # for D in /dev/sd[fjl] ; do parted $D print ; done > Model: ATA WDC WD7500BPKX-7 (scsi) > Disk /dev/sdf: 750GB > Sector size (logical/physical): 512B/4096B > Partition Table: gpt > Disk Flags: > > Number Start End Size File system Name Flags > 2 1049kB 750GB 750GB ntfs Linux RAID raid > 3 750GB 750GB 134MB ext3 Linux filesystem > > Model: ATA WDC WD7500BPKX-7 (scsi) > Disk /dev/sdj: 750GB > Sector size (logical/physical): 512B/4096B > Partition Table: gpt > Disk Flags: > > Number Start End Size File system Name Flags > 2 1049kB 750GB 750GB ntfs Linux RAID raid > 3 750GB 750GB 134MB xfs Linux filesystem > > Model: ATA Hitachi HDE72101 (scsi) > Disk /dev/sdl: 1000GB > Sector size (logical/physical): 512B/512B > Partition Table: msdos > Disk Flags: > > Number Start End Size Type File system Flags > 1 1049kB 4227MB 4226MB primary ntfs diag, type=27 > 2 4227MB 754GB 750GB primary reiserfs raid, type=fd > 3 754GB 754GB 134MB primary reiserfs type=83 > 4 754GB 1000GB 246GB primary reiserfs type=83 > > Slice 2 on each is the RAID partition, slice 3 on each is a little > filesystem for bare-bones info, and slice 4 on sdl is a normal basic > filesystem for scratch content. > > diskfarm:~ # mdadm --examine /dev/sd[fjl]2 | egrep '/dev|Name|Role|State|Checksum|Events|UUID' > /dev/sdf2: > Array UUID : 88575f01:592167fd:bd9f9ba1:a61fafc4 > Name : diskfarm:750Graid5md (local to host diskfarm) > State : clean > Device UUID : e916fc67:b8b7fc59:51440134:fa431d02 > Checksum : 43f9e7a4 - correct > Events : 720 > Device Role : Active device 1 > Array State : AAA ('A' == active, '.' == missing, 'R' == replacing) > /dev/sdj2: > Array UUID : 88575f01:592167fd:bd9f9ba1:a61fafc4 > Name : diskfarm:750Graid5md (local to host diskfarm) > State : clean > Device UUID : 0b847f84:83e80a3d:a0dc11e7:60bffc9f > Checksum : 9522782b - correct > Events : 177792 > Device Role : Active device 2 > Array State : A.A ('A' == active, '.' == missing, 'R' == replacing) > /dev/sdl2: > Array UUID : 88575f01:592167fd:bd9f9ba1:a61fafc4 > Name : diskfarm:750Graid5md (local to host diskfarm) > State : clean > Device UUID : cc53440e:cb9180e4:be4c38d4:88a676eb > Checksum : fef95256 - correct > Events : 177794 > Device Role : Active device 0 > Array State : A.. ('A' == active, '.' == missing, 'R' == replacing) > > Slice f2 looks great, but slices j2 & l2 seem to be missing -- even though > they are present. Worse, the Events counter on sdf2 is frighteningly > small. Where did it go?!? So maybe I consider sdf2 failed and reassemble > from the other two [only] and then put f2 back in? Yes I'm afraid so. I'd guess you've been running a failed raid-5 for ages, and because something hiccuped when you shut it down, the two good drives drifted apart, and now they won't start ... > > Definitely time to stop, take a deep breath, and ask for help :-) > Read up about overlays on the web site, use an overlay to force-assemble the two good drives, run fsck etc to check everything's good (you might lose a bit of data, hopefully very little), then if everything looks okay do it for real. Ie force-assemble the two good drives, then re-add the third. I'd just do a quick smartctl health check on all three drives first, just to make sure nothing is obviously wrong with them - a problem could kill your array completely! Then add the third drive back in (whether you use --add or --re-add probably won't make much difference). Oh - and fix whatever is wrong with md0, too, before that dies on you! Cheers, Wol