From mboxrd@z Thu Jan 1 00:00:00 1970 From: "NeilBrown" Subject: Re: After partition resize, RAID5 array does not assemble on boot Date: Wed, 4 Jun 2008 07:27:02 +1000 (EST) Message-ID: <48675.192.168.1.70.1212528422.squirrel@neil.brown.name> References: <4844E994.8020808@jellybean.co.uk> <4845B573.7090801@jellybean.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: <4845B573.7090801@jellybean.co.uk> Sender: linux-raid-owner@vger.kernel.org To: Jules Bean Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Wed, June 4, 2008 7:19 am, Jules Bean wrote: > Jules Bean wrote: >> Help? What next ;) Is there enough information in /dev/sdd2 and >> /dev/sdc2 to reconstruct the apparently missing superblocks on /dev/sda2 >> and /dev/sdb2? Do I need to try to resize my partitions back to their >> old size so it can find the old superblock? Even if by adding /dev/sda2 >> as a spare I've corrupted its superblock entirely, sdb2 should still >> have enough to save my array with 3 out of 4 devices? > > I have become convinced (correct me if you think I'm wrong) that the > problem was cfdisk resizing the partitions but the kernel tables not > being updated. That sounds likely.... That really should get fixed one day! > > Therefore although I thought the partitions were 400G, the kernel still > thought they were 250G, and presumably the raid subsystem used that > figure. > > So the raid subsytem probably recorded its superblock as if the > partitions were still only 250G long? So I ought to be able to find that > superblock again by resizing the partitions back? > > Alas I didn't take precise notes of my old partition table (stupid > error). I have tried a couple of cylinder counts near 250G but no luck. > Is there any good way to 'search for' somethign which looks like a RAID > superblock? > > Does the mdadm --detail output I pasted in my last message hold any clues? > Yes. Based on the "used device size", the smallest device was between 242244096K and 242244160K Hopefully both of the smaller devices were the same size. NeilBrown