From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Christensen Subject: Re: recovery from mkswap on mounted raid1 ext3 filesystem? Date: Mon, 15 May 2006 23:22:03 -0400 Message-ID: <87d5eeu010.fsf@uwo.ca> References: <87hd3qu2xu.fsf@uwo.ca> <17513.15336.921542.232057@cse.unsw.edu.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: Adrian Bunk List-Id: linux-raid.ids Neil Brown writes: > On Monday May 15, jdc@uwo.ca wrote: >> I accidentally ran mkswap on an md raid1 device which had a mounted >> ext3 filesystem on it. I also did a swapon, but I don't think >> anything was written to swap before I noticed the mistake. How much >> of the partition is toast, and is it something e2fsck might fix? > > I think (and an strace seems to confirm) that mkswap only writes in > the first 4k of the device. This will have held the superblock, but > there is always at least one backup - I think it is as block 8193. > But 'fsck -n' should help you out, though you might need > 'fsck.ext2 -n' as 'fsck' might think it is a swap device... Thanks for the quick response! I tried e2fsck, and it found the backup superblock on its own. I answered yes to dozens of questions, and the filesystem is now intact. > Ofcourse, if the filesystem is mounted, then unmounting the filesystem > should write the superblock, which might fix any corruption you > caused.. I decided to do a Alt-Sysrq-u Alt-Sysrq-b reboot to minimize what was written to disk when things were already messed up. > Adrian: You seem to be the MAINTAINER of mkswap.. any chance of > opening for O_EXCL as well as O_RDWR. That would make it a lot safer. That would have saved me lots of worry! Thanks again, Dan