Vod System Architecture And Disk Cache Strategy

With the development and integration of computer Internet and multimedia technologies,multimedia application over Internet walks into people's lives gradually. As an important aspect of multimedia over Internet,vod system developed very quickly in these years and it's application scale changes from small scale system which has only one server to large scale system which is composed with several server,so the research of the vod system faces new challenge.In large scale vod system which is composed with several server,architecture is one of factors that influence performance of vod system. Distributed architecture can conquer the shortage of single server and use communications of servers and some strategies to balance servers and components. It can improve performance and efficiency of vod system linear,so satisfy many simultaneous request. We design a distributed and data-shared hierarchical architecture which has two service levels and three storage levels.In hierarchical storage vod system,strategies of disk cache between storage levels can influence the hit rate of system's program directly,so to influence the throughput of vod system. We research dynamic and periodic strategies of disk cache for hierarchical storage architecture of vod system,based on researching the proper request model of vod system. We analyse and research replacement algorithm of disk cache that influence strategies of disk cache mostly,and propose a improved LFRU strategy and a replacement algorithm of minimum periodic frequency plus with weight.At last,we implement strategies of disk cache in programme and validate the performance of replacement algorithms of this thesis and obtain the conclusion that replacement algorithms of this thesis excelled traditional replacement algorithms.