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
