ABSTRACT
With the boom of Internet-based mass services of this decade, from massive multiplayer games to Webbased e-mail and personal pages, and additionally with the increase of corporate server farms and data storage facilities, there has been a great growth of data centers [4,20]. As an effect, energy used in data centers has been increasing: An IDC IT Experts Survey reported that in 2000, data centers consumed 1% of the total power budget of the United States; in 2005 they reached 2% of that. In 2006, data centers in the United States used59billionKWhof electricity per year, costingUS $4.1 billion andgenerating 864million metric tons of carbon dioxide (CO2) in emissions; this is expected to double in every subsequent year [20]. Moreover, the power density increases: the energy efficiency is doubling every 2 years, the performance of integrated circuits, however, triples in the same period. Hence, hardware power efficiency is offset by the increasing miniaturization and density of equipment; consequently, power draw at-the-plug will only increase [4]. Systems will keep increasing their number of cores and their power density; a recent trend in
data center provisioning is the move from individual rack-mounted servers to blade-based servers, where a set of blades is mounted in chassis with large shared power supplies. Altogether, this means that we will see hotter data centers in the near future.
