Great discussion around Red Hat’s solutions for clustering, fencing, etc, in virtualized environments.
Fencing is /very/ important for shared resources, especially disk. In a virtualized world (RHEV, VMWare, etc), fencing tools can reach right into the hypervisor to kill a failed node in a cluster. Similarly, ILO, RSA, DRAC, etc can be used to kill power to physical servers. Either way, before another node in a cluster takes over the shared resource, it is *critical* that the other node is killed. But obviously — this is an easy way to shoot yourself in the foot. As the presentors just said – “test, test, and test some more” to make sure you fencing parameters align with your deployment.