Cutting the Electric Bill for Internet-Scale Systems

Summary:

This paper investigates the potential savings large distributed internet scale systems might be able to achieve by exploiting the hourly electric price variations geographically.

The authors use real data to investigate the hour by hour variations considering pairwise locations and demonstrate that in many cases the distribution of hourly price difference is almost zero mean with high variance. This is what one needs to be able to dynamically exploit the price variations and tune the routing scheme accordingly. A one-way skewed distribution means the higher price location should probably not be used and there is no need for adaptation.

The paper proposes a bandwidth constraint routing scheme which is also adapting to real time hour by hour price variations. The amount of saving one can potentially achieve by this scheme is highly dependent on the elasticity of the distributed systems and the investigate the potential savings according to different possible elasticity and power usage efficiency scenarios.

Critique:

The paper investigates a very interesting idea. As authors point out savings are heavily influenced by energy elasticity which have been challenging researchers for a while now. Even though things are getting improved a 0% elasticity might be just too optimistic for any new future time (unless something revolutionary happens) and 40% gain under this scenario seems to be too futuristic.

The 2% gain predicted for much more realistic scenario is much more acceptable and can potentially cost few millions of dollars for a Google like system in its current status. The question will be how much this energy aware routing contradicts the current distance optimizations done for many internet systems as we have read in the literature!