[CentOS-virt] Cluster failover

hi,

I have 3 nodes of CentOS 5.3 running xen virtual machines as virtual machine service. This cluster is working fine. One thing I would like to know that how to make failover only to third node. What I mean to say is: I have 3 virtual machine running on node 1 and 2 virtual machines running on node 2. Now if node 1 fails I want my the node1 virtual machines to be stared only on node 3 but not on node2. Similary if node2 breaks, I want virtual machines to be started on node3 but never on node 1.

Thanks ! Paras.