I suspect that you may not get an answer from anyone on this issue, because I don't think anyone else has yet gotten this working on disparate physical hosts. I was trying for a while, and although I did get some suggestions that might work, I haven't had time to try again to implement it.
To be more specific, using fence_virt to manage KVM guests on different physical hosts apparently hasn't been done yet. But it would be useful to know what the behavior would be in that instance. It's possible that you might be able to sidestep the issue by treating your guests as resources managed by Pacemaker, so that the guests themselves never even know they are part of a cluster. I was going to look into this next if I couldn't figure out how to get qpid working. Date: Fri, 8 Mar 2013 12:06:32 +1000 > From: Alex Sudakar <[email protected]> > Subject: [Linux-HA] Behavior of fence_virsh if physical > host/hypervisor is down? > To: General Linux-HA mailing list <[email protected]> > Message-ID: > <CALq2s-HOmRsw4tUqjYJVEf+D9da-= > [email protected]> > Content-Type: text/plain; charset=ISO-8859-1 > > Hi. I have a simple two-node cluster which serves up a web > application in an active/passive configuration. The cluster is > running Pacemaker 1.1.7-6 and Corosync 1.4.1-7 with Red Hat Enterprise > Linux 6.3. Each node is a KVM (libvirt) virtual machine hosted on a > Red Hat Enterprise 6.3 physical host (the same host at the moment, for > testing purposes. Ultimately two separate physical hypervisor > machines at two different locations). > > I have a simple question to ask about STONITH functionality and how it > should be designed for my cluster. > > I have configured stonith agents for the two nodes using the > stonith:fence_virsh fencing agent, which works fine. If there's a > problem each node will use the appropriate resource agent to slay the > other node/VM. > > But I'm wondering what will happen if the physical machine hosting the > VM is down. > > My understanding is that a Pacemaker cluster will 'hang' if a stonith > agent fails. I've seen that mentioned in this mailing list and I've > observed this to be the case in tests of my cluster. Put in the wrong > login password for the fence_virsh agent to use and the stonith action > never succeeds and pacemaker never proceeds to redeploy its other > resources. The resources continue running as they were while the > stonith procedure fails on its continuing attempts. > > What happens if the physical host is down? If the fence_virsh agent > can't ssh into the host in the first instance, will it assume that (a) > the host is down, and therefore (b) the guest node/VM must also be > down, and thus return 'success' as to its fencing operation? Or will > it (continually) return failure and so result in the cluster > 'hanging'? > > I can't test to see what happens because I only have the one physical > host at present for my tests. :) > > Can someone advise me on what fence_virsh reports if the physical host > is down? What happens to the cluster? > > Thanks! > > > _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
