From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Robinson Subject: Re: Raid 5 rebuild with only 2 spare devices Date: Thu, 10 Feb 2011 20:07:34 +0000 Message-ID: <4D544586.4010506@anonymous.org.uk> References: <4D542872.3090102@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4D542872.3090102@gmail.com> Sender: linux-raid-owner@vger.kernel.org To: Thomas Heilberg Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 10/02/2011 18:03, Thomas Heilberg wrote: [...] > root@backup-server:/media# mdadm -D /dev/md2 > /dev/md2: > Version : 0.90 [...] > Chunk Size : 64K [...] > I also tried to recreate the raid: > > root@backup-server:/media# mdadm -Cv /dev/md2 -n3 -l5 /dev/loop0 > /dev/loop1 /dev/loop2 > mdadm: layout defaults to left-symmetric > mdadm: chunk size defaults to 512K [...] > mdadm: Defaulting to version 1.2 metadata Those loop devices are now trashed since you didn't re-create the array with exactly the parameters with which it was initially created. Your settings make me think the array was created with an older version of mdadm; the defaults for metadata version and chunk size changed a little while ago. Anyway, if you're trying again, you should specify -e 0.90 -c 64. While you're at it, add --assume-clean to avoid any rebuild, which in your case may in fact destroy good data (though the array's parity would end up consistent). Or if as you noted in your other reply you're going to have to wait 15 hours before trying anything, maybe wait until The Boss[1] makes a more intelligent suggestion than I can; he usually posts at times that appear to be overnight to me but are presumably sensible times of day for him. Cheers, John. [1] Neil Brown, who lives in Sydney where it's revoltingly early in the morning.