SpinSmart: Exploring Optimal Server Fan Speeds to Improve Overall System Energy Consumption

Abstract

Cost of data centers has risen sharply in the past few years. Today, it represents about 3% of total US energy consumption with projections to increase further in the coming years. In this paper, we focus on the server infrastructure and observe that workload consolidation techniques, which maximize power efficiency of server systems, do not automatically optimize the overall system power efficiency especially when compute engines and the corresponding on-board cooling systems are considered holistically. We design SpinSmart, a framework that explores optimal server fan speeds to minimize the overall system energy consumption. We explore core capping strategies that estimate the desired number of CPU cores to be used at any given time to minimize combined CPU+fan power. Our experimental results show that we are able to achieve 1) energy savings of up to 10% of total energy and 80% of cooling energy when compared to workload consolidation without core capping strategy; 2) cooling energy savings up to 42% when compared to the strategy that randomly assigns jobs to all the servers and cores.