Lawrence Berkeley National Laboratory

Energy consumption in data centers has recently become a major concern due to the rising operational costs and scalability issues. Recent solutions to this problem propose the principle of energy proportionality, i.e., the amount of energy consumed by the server nodes must be proportional to the amount of work performed. For data parallelism and fault tolerance purposes, most common file systems used in Map Reduce-type clusters maintain a set of replicas for each data block. A covering set is a group of nodes that together contain at least one replica of the data blocks needed for performing computing tasks. In this work, we develop and analyze algorithms to maintain energy proportionality by discovering a covering set that minimizes energy consumption while placing the remaining nodes in low power standby mode. Our algorithms can also discover covering sets in heterogeneous computing environments. In order to allow more data parallelism, we generalize our algorithms so that it can discover k-covering sets, i.e., a set of nodes that contain at least k replicas of the data blocks. Our experimental results show that we can achieve substantial energy saving without significant performance loss in diverse cluster configurations and working environments.