Management and predictions of operational changes and growth in mission critical facilities
The main challenge in understanding the cooling performance in a legacy data center is the invisible transport medium (air). This emphasizes the need for smart and meticulous measurement techniques. However, the nature of measurements is finite (e.g. top, middle and bottom) and the variation between often non-linear, therefore to capture the gradients between measured points a validated CFD simulation is needed. In this paper a brief description of an experimental characterization of a new data center lab is discussed. Airflow and temperature measurements are utilized to understand the facility's performance at different operational stages, until reaching the designed capacity. Since the facility houses a wide range of different IT equipment (servers, switches, storage and blades), it is important to understand the airflow demand of each. To do that, each type of IT was tested separately and flow characteristics were obtained (i.e. free delivery, critical pressure and flow curves). In the second part, all the characterization data is integrated via compact models into a full CFD simulation. The measured points are used for validation and the full field of air temperature and flow is resolved. Both the measurements and simulation data will now be used to answer important design, deployment and operational change questions.
Chip to Chiller Experimental Cooling Failure Analysis of Data Centers: The Interaction Between IT and Facility
Cooling failure in data centers (DCs) is a complex phenomenon due to the many interactions between the cooling infrastructure and the information technology equipment (IT). To fully understand it, a system integration philosophy is vital to the testing and design of experiment. In this paper, a facility-level DC cooling failure experiment is run and analyzed. An airside cooling failure is introduced to the facility during two different cooling set points as well as in open and contained environments. Quantitative instrumentation includes pressure differentials, tile airflow, external contour and discrete air inlet temperature, intelligent platform management interface (IPMI), and cooling system data during failure recovery. Qualitative measurements include infrared imaging and airflow visualization via smoke trace. To our knowledge of current literature, this is the first experimental study in which an actual multi-aisle facility cooling failure is run with real IT (compute, network, and storage) load in the white space. This will establish a link between variations from the facility to the central processing unit (CPU). The results show that using the external IT inlet temperature sensors, the containment configuration shows a longer available uptime (AU) during failure. However, the IPMI data show the opposite. In fact, the available uptime is reduced significantly when the external sensors are compared to internal IT analytics. The response of the IT power, CPU temperature, and fan speed shows higher values during the containment failure. This occurs because of the instantaneous formation of external impedances in the containment during failure, which renders the contained aisle to be less resilient than the open aisle. The tradeoffs between PUE, OPEX, and AU are also explained.
Open side car heat exchanger that removes entire server heat load without any added fan power
The heat dissipated by electronic equipment continues to increase at a alarming rate. This has occurred for products covering a wide range of applications. Manufacturers of this equipment require that the equipment be maintained within an environmental envelope in order to guarantee proper operation. Achievement of these environmental conditions are becoming increasingly difficult given the increases in rack heat loads and the desire for customers of such equipment to cluster racks in a small region for increased performance. And with the increased heat load of the racks and correspondingly increased air flowrate the chilled air flow supplied either through data center raised floor perforated tiles or diffusers for non raised floors is not sufficient to match the air flow required by the datacom racks. In this case some of the hot air exhausting the rear of a rack can return to the front of the rack and be ingested into the air intake thereby reducing the reliability of the electronic equipment. This paper describes a method to reduce the effect of the hot air recirculation with a water cooled heat exchanger attached to the side of a rack. This heat exchanger removes all of the heat load of a rack up to 35 kW(27° C ambient temperature and 15° C inlet water temperature) thereby having a netzero impact to the data center environmental. This paper describes the unique design of the open side car and presents the test results showing that it removes all the server heat load up to 35 kW and has minimal impact on the flow and resulting component temperatures within the server packages. This open side car design will show improvement in energy efficient heat load removal equipment compared to those currently being shipped in the marketplace.