Paying to save: Reducing cost of colocation data center via rewards

Power-hungry data centers face an urgent pressure on reducing the energy cost. The existing efforts, despite being numerous, have primarily centered around owner-operated data centers (e.g., Google), leaving another critical data center segment - colocation data center (e.g., Equinix) which rents out physical space to multiple tenants for housing their own servers - much less explored. Colocations have a major barrier to achieve cost efficiency: server power management by individual tenants is uncoordinated. This paper proposes RECO (REward for COst reduction), which shifts tenants' power management from uncoordinated to coordinated, using financial reward as a lever. RECO pays (voluntarily participating) tenants for energy reduction such that the colocation operator's overall cost is minimized. RECO incorporates the time-varying operation environment (e.g., cooling efficiency, intermittent renewables), addresses the peak power demand charge, and also proactively learns tenants' unknown responses to the offered reward. RECO includes a new feedback-based online algorithm to optimize the reward without far future offline information. We evaluate RECO using both scaled-down prototype experiments and simulations. Our results show that RECO is "win-win" and can successfully reduce the colocation operator's overall cost, by up to 27% compared to the no-incentive baseline case. Further, tenants receive financial rewards (up to 15% of their colocation costs) for "free" without violating Service Level Agreements.