Can P2P help the cloud go green?

The demand for cloud services is growing at a phenomenal rate, and so is the energy cost of the data centres powering those services. This is pressing cloud service providers to look for ways of reducing energy consumption. One approach is to utilize energy-efficient hardware and/or software in the data centres, the other approach is to relocate some services, e.g., personal files and data rendering, to end-host computers, a.k.a. peers. In the later approach, peers contribute their communication and computation resources to exchange data and provide services, while the data centre performs central administration and authentication, as well as backend processing. In this paper, we model the energy consumption for both approaches and then perform analytical studies. Our analysis shows that (1) making the data centre energy efficient can reduce the energy cost significantly; (2) the number of hops from the data centre to the peers and among peers directly influences the energy saving; (3) it is preferred to utilize peers that are already online for other purposes; (4) introducing content delivery network (CDN) servers and enabling proxy service on home modems are the keys to make a hybrid P2P-cloud network go green. We further verified these findings by simulation.