From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: Future of md multipath Date: Fri, 6 Mar 2009 16:32:09 +1100 Message-ID: <18864.46425.242906.213929@notabene.brown> References: <20090303180433.GA27569@lst.de> <18863.15828.150450.275712@notabene.brown> <20090305130017.GA1696@piper.oerlikon.madduck.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from martin f krafft on Thursday March 5 Sender: linux-raid-owner@vger.kernel.org To: martin f krafft Cc: Christoph Hellwig , linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-raid.ids On Thursday March 5, madduck@debian.org wrote: > also sprach Neil Brown [2009.03.05.0349 +0100]: > > I'm in favour of deprecating it. Whenever I hear of people using it I > > suggest dm-multipath, but there could people I don't here about. > > I think the upcoming mdadm-3.0 will need a compile-time option to > > enable multipath, so people will only get it if they really really > > want it. > > How do you propose a distro to deal with this? Keep it enabled for > a certain time (with a deprecation warning?) and then just to close > the doors on users who still need it? > > How long will you support it after deprecation? > > I understand that dm-multipath is more favourable, but unless > there's a riskless way to convert mdadm multipath into dm-multipath > on old systems, I don't think we have the option of deprecating it, > unless deprecation lasts for several years. Always the practical one, aren't you :-) I wonder how hard it would be to get mdadm to assemble a multipath using the 'dm' code rather than the 'md' code.... Or to get the md layer in the kernel to hook in to the dm multipath implementation. I think it is probably worth putting in a printk now to say "You should probably be using dm-multipath". But we probably do need to leave the code there for a while longer.. NeilBrown