1. A method for managing requests for an additional virtual machine, the method comprising: operating at least one virtual machine accessing at least one computer resource associated with at least one physical machine within a computing cluster; receiving at least one non-deterministic virtual machine request for the computer resource; modeling an over-utilization of the computer resource as a probability distribution function; based on a probability of a utilization of the computer resource being less than a probalistic bound on the over-utilization of the computer resource, allowing admission of an additional virtual machine on the physical machine associated with the computer resource, otherwise, rejecting the request for the computer resource.