Creating a RHEL Linux Cluster on vSphere 5

Hi

Is it possible to cluster RHEL linux VMs on vSphere V5 ESXi hosts?

I have some RDMs which I can add to 1 VM, but they aren't visible to add to the other VM.  These RDMs are the shared storage that the two VMs use in an active/passive RHEL cluster.

Windows clusters seem to work out of the box are there some advanced configuration parameters I need to add first?

thanks