From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian Candler Subject: Re: Using mdadm instead of dmraid for BIOS-RAID root volume Date: Thu, 10 Oct 2013 09:11:02 +0100 Message-ID: <52566116.5020604@pobox.com> References: <5253F7C2.2030401@pobox.com> <52541473.4020005@pobox.com> <52545092.1040001@arcor.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <52545092.1040001@arcor.de> Sender: linux-raid-owner@vger.kernel.org To: Martin Wilck Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 08/10/2013 19:36, Martin Wilck wrote: > On 10/08/2013 04:19 PM, Brian Candler wrote: >> > Anyway, I'm not so worried about having broken this machine, as it >> needed a reinstall anyway, but I do wonder what would have been the >> correct way to get mdraid instead of dmraid at boot time for this root >> volume? >> >> After some more searching, it looks like the udev rules were nobbled to >> disable this in >> https://bugs.launchpad.net/ubuntu/+source/mdadm/+bug/1030292 >> >> A possible way to re-enable is here: >> https://bugs.launchpad.net/ubuntu/+source/mdadm/+bug/1054948/comments/9 >> >> I'm a bit concerned about the issues around clean shutdown, and hence >> whether is really production-ready yet. > In general, this works. I have seen it work with CentOS, Fedora, and > various SUSE distributions. It may require some work on Ubuntu's side. > > 1 The udev rules for incremental mdadm autoassembly need to be in > place. The upstream rules should be fine. They can normally coexist with > the rules for dmraid. > 2 For shutdown, the distro must take care not to kill mdmon before file > systems are unmounted, and to run mdadm --wait-clean after any write > access to file systems is finished. Details of what I tried for ubuntu, and the results, are at https://bugs.launchpad.net/ubuntu/+source/mdadm/+bug/1054948/comments/16 Although it kind-of works, there are a lot of rough edges: most seriously, locking up during a shutdown. This isn't ready for production unfortunately. Also, I tried booting Ubuntu 13.10beta2, and it is still using dmraid: https://bugs.launchpad.net/ubuntu/+source/mdadm/+bug/1054948/comments/17 Regards, Brian.