From an ecological but also from an economical and in the meantime a technical view the fast ongoing increase of power consumption in today’s data centers is no longer feasible. Methodologies, more efficiently using energy in data centers, must be developed. One step into this direction is to increase the utilization of the hardware in data centers by using virtualization techniques. The efficiency of such techniques strongly depends on provisioning and allocating the resources. Statistical static allocation approaches have been proven to use resources very efficiently by overbooking hardware using the fact that typical applications rarely need their maximum demand and especially seldom all at the same time. In our work we analyze these approaches and point out two major drawbacks. First, we show that guaranteeing QoS (Quality of Service) aspects by two parameters, as it is done in these approaches, is inflexible and often leads to suboptimal solutions. Second, such conventional app...