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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91B6FC433FE for ; Tue, 18 Oct 2022 07:04:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230026AbiJRHE3 (ORCPT ); Tue, 18 Oct 2022 03:04:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230025AbiJRHEZ (ORCPT ); Tue, 18 Oct 2022 03:04:25 -0400 Received: from smtp.hosts.co.uk (smtp.hosts.co.uk [85.233.160.19]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0FEC9289 for ; Tue, 18 Oct 2022 00:04:20 -0700 (PDT) Received: from host86-161-232-249.range86-161.btcentralplus.com ([86.161.232.249] helo=[192.168.1.218]) by smtp.hosts.co.uk with esmtpa (Exim) (envelope-from ) id 1okgeA-0006Ga-4T; Tue, 18 Oct 2022 08:04:18 +0100 Message-ID: <6e6fa554-adb4-18f3-894e-e65ebcf9ccef@youngman.org.uk> Date: Tue, 18 Oct 2022 08:04:17 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.1 Subject: Re: Rebuilding mdadm RAID array after OS drive failure Content-Language: en-GB To: Steve Kolk , anthony Cc: linux-raid@vger.kernel.org, Phil Turmel , NeilBrown References: <499878ba-c52a-0041-e4b1-697bce7c9fba@youngman.org.uk> From: Wols Lists In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On 17/10/2022 23:46, Steve Kolk wrote: > I set up 3 of the drives with overlays and tried forcing the assembly, > but I still get the same error. I haven't tried the steps under > "Irreversible mdadm failure recovery", is there where I need to go > next? > > ubuntu@ubuntu:~$ echo $OVERLAYS > /dev/mapper/sda1 /dev/mapper/sdb1 /dev/mapper/sdc1 > ubuntu@ubuntu:~$ sudo mdadm --assemble --force /dev/md1 $OVERLAYS > mdadm: no recogniseable superblock on /dev/mapper/sda1 > mdadm: /dev/mapper/sda1 has no superblock - assembly aborted Sounds like you haven't understood what you're supposed to do. The whole point of overlays is it is meant to protect the underlying device while you do stuff that could be destructive. What you should be doing is setting up the overlays, then running "mdadm --create". It sounds like if you run exactly the same command as when you created the array, you'll get the original back. Read up carefully on overlays to make sure you really understand what you're doing. And then when you create the array with the overlays, if you're doing as I suggested with three drives, make sure you tell it it's a five drive array, and tell it two of the drives are missing. I'm just going to work, but whatever you do, DO NOT DO ANYTHING THAT WILL ACTUALLY WRITE TO THE DRIVES. Cheers, Wol