Graduation Year

2010

Document Type

Thesis

Degree

M.S.C.S.

Degree Granting Department

Computer Science

Major Professor

Ken Christensen, Ph.D.

Keywords

P2P, Peer-to-peer, Data center, Set-top-box, Power management

Abstract

IT equipment has been estimated to be responsible for 2% of global CO2 emissions and data centers are responsible for 1.2% of U.S. energy consumption. With the large quantity of high quality digital content available on the Internet the energy demands and environmental impact of the data centers must be addressed. The use of peer-to-peer technologies, such as BitTorrent, to distribute legal content to consumers is actively being explored as a means of reducing both file download times and the energy consumption of data centers. This approach pushes the energy use out of the data centers and into the homes of content consumers (who are also then content distributors). The current BitTorrent protocol requires that clients must be fully powered-on to be participating members in a swarm.

In this thesis, an extension to the BitTorrent protocol that utilizes long-lived knowledge of sleeping peers to enable clients to sleep when not actively distributing content yet remain responsive swarm members is developed. New peer states and events required for the protocol extension, the implementation the new protocol in a simulation environment, and the implementation of the protocol extension in a real client are described. Experiments on a simulated swarm of 51 peers transferring a 1 GB and a real swarm of 11 peers transfer- ring a 100 MB file were run. To validate the simulation a simulated swarm of 11 peers transferring a 100 MB file is compared to the real swarm of 11 peers. The results of standard BitTorrent are compared to the new Green BitTorrent by examining download times, sleep time, and awake time. The results of the experiment show significant energy savings are possible with only a small penalty in download time.

Energy savings of up to 75% are shown with download time increases as little as 10%. These energy savings could equate to over $1 billion dollars per year in the US alone if Green BitTorrent is used instead of standard BitTorrent for future rollouts of legal distribution systems.

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