Abstract

According to the 2007 EPA report to the US congress [1], the total energy use by servers in data centers in the United States amounted to about 61 billion kWh or 1.5% of the total US electricity consumption. This number is expected to nearly double in the next five years to more than 100 billion kWh, representing an annual cost of $7.4 billion and an additional 25 million metric tons of CO2 emissions. A typical data center will contain hundreds to thousands of servers, networking and storage equipment with the associated site (power and cooling) infrastructure. Approximately 50% of this energy use can be attributed to power and cooling with the remaining 50% to the server [1]. A generic 2P server consumes about 340W of power of which approximately 20-40% of this is associated with data communications for distances from a few centimeters to a few meters [2,3]. Typically, these data links are over provisioned for worst case link lengths making them power inefficient. Replacing copper with optics can realize a 5 to 7x reduction in power independent of distance. Optics with its small size, high density, low power and high bandwidth-distance connectivity will enable new system architectures which can be designed for improved air flow further reducing the power and cooling requirements within servers and data centers. Moreover, the large bandwidth capacity of optics can provide for several generations of server infrastructure. For optics to displace copper for intra-rack connections, novel low cost interconnect technologies at a cost structure comparable to copper will be required. In this presentation, we will discuss how and where optical interconnects can be used to improve server power efficiencyReferences 1. http://www.energystar.gov/ia/partners/prod_development/downloads/EPA_Datacenter_Report_Congress_Final1.pdf.2. Greg Astfalk, “Why optical communication and why now?”, Appl Phys A, Vol A 95, Number 4, pp. 933-940, June 11, 2009.3. Terry Morris, “Breaking Free of Electrical Constraints”, Appl Phys A, Vol A 95, Number 4, pp 941-944, June 11, 2009. Article not available.

© 2009 OSA, IEEE Photonics Society, SPIE, COS, CIC