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Wed, 19 May 2021 17:04:38 +0000 Received: by kubenode510.mail-prod1.omega.ne1.yahoo.com (VZM Hermes SMTP Server) with ESMTPA ID 21aa9a99aa658f9d7edcca8e558fc0a2; Wed, 19 May 2021 17:04:33 +0000 (UTC) Subject: Re: My superblocks have gone missing, can't reassemble raid5 To: antlists , Linux RAID References: From: Leslie Rhorer Message-ID: Date: Wed, 19 May 2021 12:03:50 -0500 User-Agent: Mozilla/5.0 (Windows NT 6.1; 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-US Content-Transfer-Encoding: 8bit X-Mailer: WebService/1.1.18291 mail.backend.jedi.jws.acl:role.jedi.acl.token.atz.jws.hermes.yahoo Apache-HttpAsyncClient/4.1.4 (Java/16) Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On 5/19/2021 11:41 AM, antlists wrote: > 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? That is one reason, yes. It also means no mater what else, I know what the system is being told to do. >>      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. No, I am not. > 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. Absolutely. So what? If it does, very little time and no data whatsoever is lost. If it doesn't fail, then his problem is solved with very little trouble. I have been troubleshooting technical issues for well over 50 years, and one of the very first lessons I learned is one should try the simplest solutions first. Whenever they work, they can save a tremendous amount of time and effort. After that, it's time to dig out the heavy tools.