I worked on Penguin's HPC offering a few years back. It PXE boots all of the compute nodes in a lightweight manner, and builds the entire cluter into a single process space. Distributed process space means that a signal sent to a parent process running on one node gets correctly forwarded to a child process running on another. You will not find an easier way to manage the cluster than Scyld.
It can install on top of Red Hat Enterprise Linux or the Comparable CentOS