Abstract: Rapid developments of distributed systems，networking technologies，and multi-media technologies are bringing us a possibility to access remote huge-media-data on-line.Distributed Media Service System becomes hot topic of current researches and developments.One of the great challenges in VoD domain is to optimize the performance/cost ratio of the designed systems.In this paper，the design and implementation of a clustered，high performance，high availability and low cost VoD system—CVoD is presents，which is based on a network of PC.Through the experimental test of the prototype of CVoD，CVoD succeeds to server 90 near DVD quality streams per node，having great potentials for further expanding.With the scaling of CVoD，the results of our experimental test prove the linear relationship between the number of server nodes and the number of served streams that can be concurrently serviced by CVoD.The main inhibitory factor for further expanding of the system is the network bandwidth.The results of experimental test prove that CVoD has good performance expandability and high availability.

摘要： 随着分布式系统、网络技术和多媒体技术的迅速发展，使得联机访问异地巨量媒体数据成为可能，从而形成了当前研究和开发的热点——分布式媒体服务系统。优化VoD系统的性能以及降低系统的成本是设计VoD系统的一个重要挑战。描述了一种基于PC机集群系统的高性能、高可用性以及低成本的集群VoD系统——CVoD的设计及其实现。对该系统进行的性能测试表明，每个节点能够服务大约90个近似于DVD质量的视频流；随着集群系统规模的扩大，该系统能够服务的客户端和系统中的服务器节点的个数基本上成正比，限制系统性能进一步扩展的关键因素是网络带宽大小的限制。实验结果证明CVoD具有很好的性能可扩展性以及良好的可用性。