Abstract

Data center power consumption is growing to unprece-dented levels: the EPA estimates U.S. data centers will con-sume 100 billion kilowatt hours annually by 2011. Much of this energy is wasted in idle systems: in typical deployments, server utilization is below 30%, but idle servers still con-sume 60 % of their peak power draw. Typical idle periods— though frequent—last seconds or less, confounding simple energy-conservation approaches. In this paper, we propose PowerNap, an energy-conservation approach where the entire system transitions rapidly be-tween a high-performance active state and a near-zero-power idle state in response to instantaneous load. Rather than requiring fine-grained power-performance states and complex load-proportional operation from each system com-ponent, PowerNap instead calls for minimizing idle power and transition time, which are simpler optimization goals. Based on the PowerNap concept, we develop requirements and outline mechanisms to eliminate idle power waste in en-terprise blade servers. Because PowerNap operates in low-efficiency regions of current blade center power supplies, we introduce the Redundant Array for Inexpensive Load Shar-ing (RAILS), a power provisioning approach that provides high conversion efficiency across the entire range of Power-Nap’s power demands. Using utilization traces collected from enterprise-scale commercial deployments, we demon-strate that, together, PowerNap and RAILS reduce average server power consumption by 74%.