From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Freemyer Subject: Re: mirroring: [patch 1 of 8] device failure tolerance Date: Thu, 30 Jun 2005 12:38:17 -0400 Message-ID: <87f94c370506300938213c1ad8@mail.gmail.com> References: <16a7b346170f3909d57592016a32abc0@redhat.com> <87f94c37050630081370347a28@mail.gmail.com> <3333970fb0e372a4637169a2b97b46f7@redhat.com> Reply-To: Greg Freemyer , device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <3333970fb0e372a4637169a2b97b46f7@redhat.com> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Jonathan E Brassow Cc: device-mapper development List-Id: dm-devel.ids On 6/30/05, Jonathan E Brassow wrote: >=20 > On Jun 30, 2005, at 10:13 AM, Greg Freemyer wrote: >=20 > > On 6/29/05, Jonathan E Brassow wrote: > >> This patch defines a couple more states that logs can return, and > >> checks for those states in the mirror code. The states are useful f= or > >> logs that have cluster support. > >> > >> brassow > > > > Have I been asleep? This is the first I heard of DM having cluster > > mirror support. I assume the goal is something along the lines of > > what DRBD provides. > > > > Can someone give a very high-level overview of current status, plans, > > etc. related to DM Cluster Mirror support. And if this related to th= e > > DRBD project? >=20 > Please note that the "mirroring [patch x of 8]..." set for device fault > tolerance has been replaced with the "mirroring [patch x of 6]..." set. >=20 > The cluster mirroring that I'm talking about is active/active and > capable of handling more than 2 nodes. It would be used in conjunction > with a clustered file system - like GFS. The application sitting on > the cluster mirror should be cluster-aware. You wouldn't be able to > just put ext3 on there and expect it to work in a cluster capacity. >=20 > Although there are some minor things that need to happen in the mirror > proper code (as can be seen from the smallness of the cluster patch), > the heavy lifting is done by a cluster-aware log. That is were you are > keeping track of clean/dirty/recovering state. >=20 > An out-dated (but still useful for background) dock can be found at > http://www.brassow.com/mirroring/index.html >=20 > brassow >=20 Sounds like you have more ambitious plans than DRBD. (They have active-passive now and IIRC they plan the next major release to have active-active, but I think only on 2 nodes.) Is the GFS team planning on supporting this infrastructure. I hope so. Greg --=20 Greg Freemyer The Norcross Group Forensics for the 21st Century