From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phil Turmel Subject: Re: dm-crypt over raid6 unreadable after crash Date: Sun, 10 Jul 2011 08:28:27 -0400 Message-ID: <4E199AEB.4030606@turmel.org> References: <20110706161228.GA1491@apartia.fr> <4E1494BB.9060101@turmel.org> <20110707090540.GA7288@apartia.fr> <4E15A980.3060508@turmel.org> <20110707130917.GA18812@apartia.fr> <4E15B576.9040004@turmel.org> <20110708054045.GA28420@maude.comedia.it> <20110710120350.GA30568@apartia.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110710120350.GA30568@apartia.fr> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 07/10/2011 08:03 AM, Louis-David Mitterrand wrote: > On Fri, Jul 08, 2011 at 07:40:45AM +0200, Luca Berra wrote: >>> This is important. When I computed the sector count for the linear mapping, I just took 2048 off the end. You may want to select a sector count that aligns the endpoint. >> but the xfs sb should be at sector 0 > > So what should I change to the dmsetup command to make it work? He means (not to put words in Luca's mouth...) that the precise endpoint of the mapped volume shouldn't matter to fsck.xfs. Changing device order in the raid is probably your only hope of recovery. The dmsetup exercise was a blind alley. Luca also pointed out that the problem array is named "grml" which means that it was created with grml, not your original system (zenon). That suggests that "mdadm --create" was used under grml, and the member devices were specified in an order differing from the original install. If that "mdadm --create" didn't include the "--assume-clean" option, then the parity blocks are almost certainly recomputed, and your data destroyed. Otherwise, you can try "mdadm --create --assume-clean" with other combinations of device order to try to find the "right" one. I recommend trying "mdadm --create --assume-clean" with the devices in the same order as shown by lsdrv for the zenon array. Phil