说明：  针对分布式媒体服务系统中的副本放置问题，从优化节点间的传输代价出发，提出一种基于全局信息的启发式副本放置算法—— Zero2min，与现有算法相比，节省传输代价10 ~36 。根据Zero2min 算法的思路，给出媒体内容逐渐增加情况下的一种动态放置方法，仿真结果表明，其代价小于Max2min。
(Aiming at the problem of replica placement in a distributed media system to reduce the cost of transferring data among nodes, this paper proposes an heuristic replica placement algorithm——Zero2min based on global information, compared with common algorithm, its cost is reduced by 10 ~36 . It further proposes a method to place the media data when the data is imported into the system. Simulation results show that its cost is less than Max2min.)