From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniele patoner Subject: Re: Using xen and drbd/migration Date: Fri, 10 Jun 2005 13:02:03 +0200 Message-ID: <42A9732B.3000201@biblio.unitn.it> References: <001501c56d9e$680e86d0$0f01a8c0@zaphod> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <001501c56d9e$680e86d0$0f01a8c0@zaphod> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org I have successfully migrated domU with gnbd, but with a third host C that export the root filesystem, but IMHO support for drbd is a nice feature for High-Affidability purpose with xen. http://sources.redhat.com/cluster/gnbd/gnbd_usage.txt Daniele Michael Paesold wrote: > Hello, > > short introduction, my name is Michael Paesold, I am student from > Austria/Europe and I am currently evaluating high availability and > virtualization technologies for Linux/Unix. > > What I want to do is to use xen with a drbd[1] device as root for a domU > and then be able to migrate the domU between two host systems. I have > already read the documenation on xen and some papers[2] and searched > through the archives about drbd/xen usage. Unfortunatly my questions are > not covered anywhere, so I hope you can help me. > > drbd would run in the domain 0 to replicate a block device, say > /dev/drbd0 on host A and host B. Xen would be set up on both hosts. > On host A I would create a new VM with /dev/drbd0 as root. > > drbd will now sync /dev/drbd0 from host A to host B and keep those two > consistent. Nevertheless in a drbd setup only on host can be primary and > only one host may access a device (read/write). > > So a live migration of a VM from host A to B would have to look like this: > > pre-copy migration > suspend VM on A > stop-and-copy phase > --> on A: drbdadm secondary drbd0 # make A secondary for /dev/drbd0 > --> on B: drbdadm primary drbd0 # make B primary for /dev/drbd0 > resume VM on B > > (with the root now pointing to the local /dev/drbd0 device) > > Is there a way to do this with xen 2.0 or 3.0? > > If no, I think a way would be to implement a module interface for the > migration so that one can setup the environment after the VM is stop, > but before the VM is resumed on the new host. > > Ideas? > > Best Regards, > Michael Paesold > > [1] distributed remote block device - http://www.drbd.org/ > [2] e.g. > http://www.cl.cam.ac.uk/Research/SRG/netos/papers/2005-migration-nsdi-pre.pdf > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel >