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 697ECC433ED for ; Wed, 19 May 2021 16:41:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3CF3561244 for ; Wed, 19 May 2021 16:41:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355354AbhESQms (ORCPT ); Wed, 19 May 2021 12:42:48 -0400 Received: from smtp.hosts.co.uk ([85.233.160.19]:39950 "EHLO smtp.hosts.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355170AbhESQmr (ORCPT ); Wed, 19 May 2021 12:42:47 -0400 Received: from host109-154-217-227.range109-154.btcentralplus.com ([109.154.217.227] helo=[192.168.1.65]) by smtp.hosts.co.uk with esmtpa (Exim) (envelope-from ) id 1ljPGA-0005ni-Eq; Wed, 19 May 2021 17:41:26 +0100 Subject: Re: My superblocks have gone missing, can't reassemble raid5 To: Leslie Rhorer , Linux RAID References: From: antlists Message-ID: Date: Wed, 19 May 2021 17:41:29 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On 19/05/2021 15:48, Leslie Rhorer wrote: >     Then I would try recreating the RAID based upon the earlier Examine > report: > > mdadm -C -f -n 3 -l 5 -e 1.2 -c 512 -p ls /dev/md99 /dev/loop2 > /dev/loop0 /dev/loop1 > >     You may notice some of the command switches are defaults.  Remember > what I said about a belt and suspenders?  Personally, in such a case I > would not rely on defaults. Because defaults change? > >     Now try running a check on the assembled array: > fsck /dev/md99 > >     If that fails, shutdown the array with > > mdadm -S /dev/md99 > >     and then try creating the array with a different drive order. > There are only two other possible permutations of three disks.  If none > of those work, you have some more serious problems. And here you are oversimplifying the problem immensely. If those three drives aren't the originals, then the chances are HIGH that a simple re-assembly/creation is going to fail your simplistic scenario. That said, I couldn't agree more about getting new drive(s) to take a backup before attempting recovery ... Cheers, Wol