From mboxrd@z Thu Jan 1 00:00:00 1970 From: Giovanni Tessore Subject: Re: Can this setup be saved? Date: Sat, 13 Feb 2010 09:58:03 +0100 Message-ID: <4B76699B.5060202@texsoft.it> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids > I've made a mess of my raid setup and am desperately trying to save > it. The setup is RAID-5 on 3 SATA disks. Problems started with one of > the disks getting unrecoverable read errors. Unfortunately I was away > on a trip and the machine was used by my family while this was going > on :( > > Array consists of three devices: /dev/sda2, /dev/sdc2, and /dev/sdd2. > When I got back from the trip I found the following: > > 1. Two disks were removed from the array, leaving only /dev/sda2; > 2. When either of the two was added, the array would start; > 3. One combination of two disks (/dev/sda2 + /dev/sdd2) aproduced a > running /dev/md0 with a proper ext3 filesystem seen on the drive (even > passing fsck); > > At this point I added /dev/sdc2 and the reconstruction started. > However did not complete, since /dev/sdd2 has unrecoverable errors. > Reading the list archives I figured I need another drive to ddrescue > /dev/sdd2, then perform the reconstruction. > > However at some point during/after the reconstruction the situation > has changed. Now both /dev/sdc2 and /dev/sdd2 are marked as spare > drives (see mdadm -E output below) and I cannot start the array. I > think /dev/sdd2 should be in sync with /dev/sda2, but how can I bring > it back (it used to be device 2) I recently had similar problem with a 6 disk array, when one died and another gave read errors during reconstruction, this is my experience: I was able to recover most data reassembling the array and copying data from it to another storage; I used a command like: mdadm --create /dev/md3 --assume-clean --level=5 --raid-devices=6 --spare-devices=0 /dev/sda4 /dev/sdb4 /dev/sdc4 /dev/sdd4 /dev/sde4 missing where /dev/sdf4 was the dead disk, which i left out as missing, and /dev/sdb4 was the one which gave read errors; missing a disk avoids starting the reconstruction. It's important to set the md device in read-only mode (if supported by mdadm version can use the --readonly option directly with the --create command, see man mdadm), and to mount the device readonly. This mostly worked for me (lost 100Gb over 2.5Tb) I hope you can recover your data. Regards -- Cordiali saluti. Yours faithfully. Giovanni Tessore