I am doing some research on how to build a cluster with commodity hardware and some free operating systems (Like Linux plus others like FreeBSD). The installation and configuration of OpenMPI was pretty strait forward for me when setting things up on the server but what I want to know now is what do to have to do to the nodes for the cluster to start working like a cluster.

Also what types of settings do I have to make in the NFS side, Can i share the entire hard drive or do I absolutely need to only share the home directory of one of the users