From mboxrd@z Thu Jan 1 00:00:00 1970 From: Flemming Frandsen Subject: DM vs. MD: The showdown Date: Tue, 5 May 2009 14:51:39 +0200 Message-ID: <4A00365B.7030500@stibo.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: dm-devel@redhat.com List-Id: dm-devel.ids I've searched high and low for any info, but my google-fu has failed me, so feel free to redirect me to a more appropriate mailing list or documentation if this is too OT. I have a box that had a working md RAID 1+0 setup, iow: * /dev/md1 is a mirror containing /dev/sda2 and /dev/sdc2 * /dev/md2 is a mirror containing /dev/sdb2 and /dev/sdd2 * /dev/md3 is a stripe set of /dev/md1 and /dev/md2 The problem is that I recently had to enable multipath to hook up to the SAN, that part went ok, but afterwards my /proc/mdstat shows that dm seems to have renamed all my disks: md1 : active raid1 dm-2[0] 48829440 blocks [2/1] [U_] md2 : active raid1 dm-3[0] 48829440 blocks [2/1] [U_] and mdadm can no longer create md3 because: mdadm: no devices found for /dev/md3. For some reason dm has found it funny to grab the md1 and md2 mirrors and use them to create the stripe set: /dev/mapper/md|md3 I've mounted the /dev/mapper/md|md3 device and it seems to contain my file system, but I'd really like to get dm out of the way and only use it to handle the multipath bits needed for the SAN. How do I tell dm to keep its paws to itself? I'm running Linux 2.6.20 (on a Ubuntu 7.04), btw. -- Regards Flemming Frandsen - Stibo Systems - DK - STEP Release Manager