A holistic and optimal approach for data center cooling management

Abstract

Efficient and reliable operation of today's data centers, which host IT equipment with ever-increasing power density, relies heavily on the cooling system to meet the thermal management needs of the IT equipment with minimal environmental footprint. The dynamic IT workload, together with the spatial variance of cooling efficiencies, creates both temporal and spatial non-uniformities within the data centers. Most data centers use zonal cooling actuators, such as computer room air conditioners (CRAC), to alleviate the local "hot spots". Without proper localized cooling actuation mechanisms, the cooling capacity is usually over-provisioned that leads to waste of energy. To address this problem, we introduce adaptive vent tiles (AVT) for local cooling adjustment, and develop a holistic multivariable model based on the mass and energy balance principles to capture the effects of both zonal and local cooling actuation on the inlet temperatures of the racks that host the IT equipment. A model predictive controller is then proposed to minimize the total cooling power while meeting the thermal requirements of the racks. The zonal and local cooling actuation is coordinated in such a unified framework for the provisioning, transport and distribution of the cooling resources in the data centers. The proposed holistic cooling approach is validated in a production data center. Experimental results indicate that up to 36% of CRAC units blower power can be saved, compared with the state of the art control solution.