Re: What am I missing?
Most clustering software (including OS level) requires direct hardware access to a shared disk somewhere. -- in Vmware language, device passthrough. Once done, typically, your VM is now pinned to a specific node. This applies for most OS clusters, Oracle RAC, Vertias, MCSG and a number of applications I've had to deploy in the past.
To my knowledge, RH has fixed RHCS for VMware and kvm environments, and the MCSG for linux incorporated a similar fix - I believe that Vertias clusters now can *have* virtual nodes, but any master must NOT be virtual - I've not worked with them recently.
I still have DBA's talking about putting RAC clusters in virtualization - to whit, we have an exadata coming shortly to solve that issue.