Is the "real" memory allocated to Xen DomU machines paged by the Dom0
machine?  Put another way, the machine has a certain amount of RAM.  What
are my choices for allocation among several DomUs?  It's obviously bad to
overcommit too much, resulting in double-paging, but am I restricted to
the total amount of real memory in assigning memory sizes to the VMs?

		--Steven M. Bellovin, http://www.cs.columbia.edu/~smb