On 22/06/16 01:01 AM, Tom Robinson wrote: > Hi, > > I have two KVM hosts (CentOS 7) and would like them to operate as High Availability servers, > automatically migrating guests when one of the hosts goes down. > > My question is: Is this even possible? All the documentation for HA that I've found appears to not > do this. Am I missing something? Very possible. It's all I've done for years now. https://alteeve.ca/w/AN!Cluster_Tutorial_2 That's for EL 6, but the basic concepts port perfectly. In EL7, just change out cman + rgmanager for pacemaker. The commands change, but the concepts don't. Also, we use DRBD but you can conceptually swap that for "SAN" and the logic is the same (though I would argue that a SAN is less reliable). There is an active mailing list for HA clustering, too: http://clusterlabs.org/mailman/listinfo/users > My configuration so fare includes: > > * SAN Storage Volumes for raw device mappings for guest vms (single volume per guest). > * multipathing of iSCSI and Infiniband paths to raw devices > * live migration of guests works > * a cluster configuration (pcs, corosync, pacemaker) > > Currently when I migrate a guest, I can all too easily start it up on both hosts! There must be some > way to fence these off but I'm just not sure how to do this. Fencing, exactly. What we do is create a small /shared/definitions (on gfs2) to host the VM XML definitions and then undefine the VMs from the nodes. This makes the servers disappear on non-cluster aware tools, like virsh/virt-manager. Pacemaker can still start the servers just fine and pacemaker, with fencing, makes sure that the server is only ever running on one node at a time. > Any help is appreciated. > > Kind regards, > Tom We also have an active freenode IRC channel; #clusterlabs. Stop on by and say hello. :) -- Digimer Papers and Projects: https://alteeve.ca/w/ What if the cure for cancer is trapped in the mind of a person without access to education?