Reducing the Power Costs of Content Distribution Networks Using Batteries

Open Access
Palasamudram, Darshan Suresh
Graduate Program:
Computer Science and Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
February 27, 2013
Committee Members:
  • Bhuvan Urgaonkar, Thesis Advisor
  • Batteries
  • Power
  • CDN
Data centers are growing in terms of size and usage; as a result they are one among the dominant consumers of electricity today. If the consumption of electricity by data centers is treated as a country, then it becomes the fth in the world for electricity use. Hence the need to reduce the peak power demand in data centers is a hot topic of research. There has been various techniques proposed to do this. Our study focuses on one of the Internet-Scale networks and reducing the power cost by using batteries (such as Akamai). The operating expenses of large distributed networks are increasingly driven by the cost of supplying power to their servers. Typically, CDNs procure power through long-term contracts from co-location providers and pay on the basis of the power (KWs) provisioned for them, rather than on the basis of the energy (KWHs) actually consumed. We propose the use of batteries to reduce both the required power supply and the incurred power cost of a CDN. We provide a theoretical model and an algorithmic framework for provisioning batteries to minimize the total power supply and the total power costs of a CDN. We evaluate our battery provisioning algorithms using extensive load traces derived from Akamai's CDN to empirically study the achievable bene ts. We show that batteries can provide up to 14% power savings, that would increase to 22% for more power-proportional next-generation servers, and would increase even more to 35.3% for perfectly power-proportional servers. Likewise, the cost savings, inclusive of the additional battery costs, range from 13.26% to 33.8% as servers become more power-proportional. Further, much of these savings can be achieved with a small cycle rate of one full discharge/charge cycle every three days that is conducive to satisfactory battery lifetimes. In summary, we show that a CDN can utilize batteries to signi cantly reduce both the total supplied power and the total power costs, thereby establishing batteries as a key element in future distributed network architecture. While we use the canonical example of a CDN, our results also apply to other similar Internet-scale distributed networks.