This may seems a bit of a strange question, but has any thought been given to merging the ideas of Xen with Mosix? A client asked me this, and I can't come up with a clear answer. I understand that both provide clustering, but at a different granularity. A Xen cluster can migrate an entire server OS environment, while a Mosix cluster migrates specific processes.

I presume there is a basic assumption to Xen usage that the hardware resource pool, represented by the resources of any single physical computer system, smp or not, is always mayfold greater than the demands of any guest domain. Many OS images running concurently on the same machine is the idea. As a side effect, the resource usage of any on OS environment is also limited at a maximum by the limites on any single node machine. (It's also limited by configuration, I know.)

Would building Xen on top of Mosix allow that resource pool to expand to that of the entire Mosix cluster?

This would, if feasible, allow not only more domains to be managed by a single Xen kernel, but also allow dynamic expansion of single domain images beyond the limits of single hardware nodes.