From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc MERLIN Subject: Re: mdadm create corrupted md data? Date: Tue, 6 May 2008 16:08:00 -0700 Message-ID: <20080506230800.GL31536@merlins.org> References: <20080506054819.GA6413@merlins.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20080506054819.GA6413@merlins.org> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: richard@sauce.co.nz List-Id: linux-raid.ids [please Cc me on replies, I see them faster that way] On Mon, May 05, 2008 at 10:48:19PM -0700, Marc MERLIN wrote: > I thought I could recreate a n-1 array like so: > gargamel:~# mdadm --create /dev/md5 --level=5 --chunk=64 --layout=left-symmetric --raid-devices=5 /dev/sd{c,d,f,g}1 > mdadm: You haven't given enough devices (real or missing) to create this array > > In the olden days (pre-mdadm), I could bring up the array by giving 5 drives > and marking /dev/sde1 as failed-disk instead of read-disk (or somesuch). Indeed "missing" as a device name did it, thanks Richard (I guess I can't read when it's late). Sad part is that recreating the device worked, but my VG on top disappeared. I may have found a bug or misfeature. During my first post, and up to this mornhing, I had: Layout : left-symmetric Chunk Size : 64K md5 : active raid5 sdf1[0] sdc1[3] sdg1[2] sde1[1] 1953535744 blocks level 5, 64k chunk, algorithm 2 [5/4] [UUUU_] pvdisplay /dev/md5 or vgscan would find the pv and vg. Then, I just typed this: mdadm --create /dev/md5 --level=5 --raid-devices=5 /dev/sd{c,d,f,g}1 missing it made a new md5 that vgscan doesn't find anything on. but I'm very confused as to why mdadm --create /dev/md5 --level=5 --raid-devices=5 /dev/sd{c,e,f,g}1 missing also gives me an md5 that vgscan won't find its pv on anymore gargamel:~# cat /proc/mdstat | grep -1 md5 | tail -n+2 md5 : active raid5 sdg1[3] sdf1[2] sde1[1] sdc1[0] 1953535744 blocks level 5, 64k chunk, algorithm 2 [5/4] [UUUU_] gargamel:~# pvdisplay /dev/md5 No physical volume label read from /dev/md5 Failed to read physical volume "/dev/md5" Any idea what got corrupted in my mdadm runs that caused my data to apparently be gone now? (good news is that I do have an up to date backup, but I should have to use it, and I'd like to recover from this the way it should work, so that I can learn from it) It's maybe a good time to give: 2.6.24.5-slub-dualcore2smp-volpreempt-noticks and mdadm - v2.6.4 - 19th October 2007 Even if I've lost my data, I'd still like to try to find out what went wrong and help debug if that helps. Thanks, Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems & security .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/