Thermal performance modeling of hybrid liquid-air cooled servers

This paper discusses data center scale performance characterization of hybrid liquid-air cooling solutions for a full 42U rack of servers. Using data collected in a production data center at Lawrence Berkeley Laboratories, we interpret the results with a simple three parameter model which allows characterization of the major factors affecting heat recovery efficiency of the system. The model is shown to agree with a broad set of data under a variety of temperature and workload conditions. To our knowledge, this is the first large scale characterization of a hybrid cooling solution's performance in terms relevant to data center operation. We discuss how this method can be extended to other systems for meaningful comparison of solution performance.