From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Tran Subject: Re: data recovery on raid5 Date: Fri, 21 Apr 2006 18:31:03 -0500 Message-ID: <44496B37.6040501@us.ibm.com> References: <8867c2a014b34d9c11ce162c4f5860af@coraid.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <8867c2a014b34d9c11ce162c4f5860af@coraid.com> Sender: linux-raid-owner@vger.kernel.org To: Sam Hopkins Cc: linux-raid@vger.kernel.org, jrs@abhost.net, support@coraid.com List-Id: linux-raid.ids Sam Hopkins wrote: >Hello, > >I have a client with a failed raid5 that is in desperate need of the >data that's on the raid. The attached file holds the mdadm -E >superblocks that are hopefully the keys to the puzzle. Linux-raid >folks, if you can give any help here it would be much appreciated. > ># mdadm -V >mdadm - v1.7.0 - 11 August 2004 ># uname -a >Linux hazel 2.6.13-gentoo-r5 #1 SMP Sat Jan 21 13:24:15 PST 2006 i686 Intel(R) Pentium(R) 4 CPU 2.40GHz GenuineIntel GNU/Linux > >Here's my take: > >Logfiles show that last night drive /dev/etherd/e0.4 failed and around >noon today /dev/etherd/e0.0 failed. This jibes with the superblock >dates and info. > >My assessment is that since the last known good configuration was >0 >1 /dev/etherd/e0.0 >2 /dev/etherd/e0.2 >3 /dev/etherd/e0.3 > >then we should shoot for this. I couldn't figure out how to get there >using mdadm -A since /dev/etherd/e0.0 isn't in sync with e0.2 or e0.3. >If anyone can suggest a way to get this back using -A, please chime in. > >The alternative is to recreate the array with this configuration hoping >the data blocks will all line up properly so the filesystem can be mounted >and data retrieved. It looks like the following command is the right >way to do this, but not being an expert I (and the client) would like >someone else to verify the sanity of this approach. > >Will > >mdadm -C /dev/md0 -n 4 -l 5 missing /dev/etherd/e0.[023] > >do what we want? > >Linux-raid folks, please reply-to-all as we're probably all not on >the list. > > > Yes, I would re-create the array with 1 missing disk. mount read-only, verify your data. If things are ok, remount read-write and remember to add a new disk to fix the degrade array. With the "missing" keyword, no resync/recovery, thus the data on disk will be intact. -- Regards, Mike T.