Using a Potential Game for Power Reduction in Distributed Storage Systems

We present a game-theoretic approach for power reduction in large-scale distributed storage systems. The key idea is to use distributed hash tables to dynamically migrate virtual nodes, thus skewing the workload towards a subset of physical disks without overloading them. To realize this idea in an autonomous way (i.e., without any kind of central controller), virtual nodes are considered to be selfish agents playing a game in which each node receives a payoff according to the workload of the disk on which it currently resides. We model this setting as a potential game, where an increase in the payoff to a virtual node reduces the power of the system. This game consists of a pair of global and private utility functions, derived by means of the Wonderful Life Utility technique. The former function evaluates the state of the system, and the latter provides criteria for the migration of each node. The performance of our method is measured by simulations and a prototype implementation. From these evaluations, we find that our method reduces the running time of the disks in active mode by 12.7-18.7%, with an overall average response time of 50-190 ms.