Achieving energy-efficient operation of information and communication (ICT) technology has become one of society's primary objectives, being actively investigated in research and development. It is estimated that 8–10% of global carbon dioxide (CO2) emissions are because of the ICT industry (http://www.vertatique.com/ict-10-global-energy-consumption, http://europa.eu/rapid/press-release_IP-13-231_en.htm).
Data centers play an essential role in today's ICT infrastructure by serving as the backbone for many kinds of electronic services. They make up a significant part of ICT's total energy consumption, accounting for 23% of ICT's global CO2 emissions (http://www.gartner.com/it/page.jsp?id=530912). It is assumed that in the United States all data centers combined consumed between 1.7% and 2.2% of the total US electricity consumption in 2010, while worldwide data center energy consumption was around 1.3% .
This amount is certainly significant, and data center operators and researchers are working hard to reduce data center energy consumption. Approaches toward increasing data center energy efficiency mainly target computing, storage, the network, and cooling infrastructure individually or in a joint way, as illustrated in Figure 16.1. Computing nodes, including high-end, mid-range, and volume servers, ...