为节省云存储系统的能耗，文中考虑在云存储系统利用率较低时关闭部分存储节点．为了保证部分存储节点关闭时数据的可用性，针对如何选择云存储系统中可以关闭的节点集合问题，设计了基于辅助节点的贪心算法， 并针对异构云存储系统的能耗优化问题，提出了面向异构云存储系统的能耗优化贪心算法．模拟实验结果表明，文中提出的面向异构系统的能耗优化贪心算法能较好地降低异构云存储系统的能耗，其性能明显优于一般的贪心算法，从而验证了所提算法的有效性．

In order to reduce the energy consumption of cloud storage systems,a method to save energy by turningoff some storage nodes in inactive periods is proposed.Then,for the purpose of guaranteeing the availability of datawhen part of storage nodes are turned off,an auxiliary node- based greedy algorithm is designed to properly selectstorage nodes to form a turned- off node set.Moreover,an improved auxiliary node- based greedy algorithm for hete-rogeneous storage systems is proposed for the optimization of energy consumption.Simulated results show that theimproved auxiliary nod- based greedy algorithm is effective because it greatly reduces the energy consumption of he-terogeneous cloud storage systems and outperforms the conventional greedy algorithm.