Barely Alive Servers: Greener Datacenters Through Memory-Accessible, Low-Power States

Current resource provisioning schemes in Internet services leave servers less than 50% utilized almost all the time. At this level of utilization, the servers’ energy efficiency is substantially lower than at peak utilization. A solution to this problem could be dynamically consolidating workloads into fewer servers and turning others off. However, services typically resist doing so, because of high response times during re-activation in handling traffic spikes. Moreover, services often want the memory and/or storage of all servers to be readily available at all times. In this paper, we propose a family of barely-alive active low-power server states that facilitates both fast re-activation and access to memory while in a low-power state. We compare these states to previously proposed active and idle states. In particular, we investigate the impact of load bursts in each energy-saving scheme. We also evaluate the additional benefits of memory access under low-power states with a study of a search service using a cooperative main-memory cache. Finally, we further investigate our barely-alive states in two case studies: (1) a mixed system that combines a barely-alive state with the off state to maximize energy savings; and (2) a barely-alive system that facilitates hosting more than one service at the same time. We find that the barely-alive states can reduce service energy consumption by up to 38%, compared to an energy-oblivious system. These energy savings are consistent across a large parameter space. In the presence of two services, the barely-alive system can reduce energy consuption by 34% over a two-system deployment. Vlasia Anagnostopoulou⋆ (e-mail: [email protected]), Susmit Biswas⋆ (e-mail: [email protected]), Heba Saadeldeen⋆ (e-mail: [email protected]), Alan Savage⋆ (e-mail: [email protected]), Ricardo Bianchini† (e-mail: [email protected]), Tao Yang⋆ (e-mail: [email protected]), Diana Franklin⋆ (e-mail: [email protected]) and Frederic T. Chong⋆ (e-mail: [email protected]) ⋆University of California Santa Barbara, Santa Barbara, CA 93106 †Rutgers University, Piscataway, NJ 08854