大规模层次化视频点播存储系统的设计与管理

近来计算机和通信技术的发展使得视频点播（video-on-demand,简称VOD)在技术和经济上成为可能.连续媒体的特性使得VOD系统需要大规模的存储服务器.层次化存储体系是减少系统费用的合理方案.文章提出了一种层次化的存储模型和磁盘cache的概念.根据这个模型,提出了基于访问频率的替换算法,并对算法的有效性进行了模拟和分析.结果表明,这种算法解决了LFU(least frequently used)算法中的“cache污染”（cache pollution）问题,能较好地适用于连续媒体数据应用.

Design and Management of Large Scale Hierarchical VOD Storage System

Recent advances in computing and communication technologies have made VOD (videoondemand) technically feasible and economically. The VOD system needs massive storage server because of the characteristic of the continuous media. Hierarchical storage is a good solution for the system under low cost. In this article, the authors first propose a hierarchical architecture model and the concept of disk cache, then develop a replacement algorithm based on access frequency by the model, finally analyse and simulate the algorithm. The results show that the algorithm avoids cache pollution problem in LFU (least frequently used) algorithm and well suits the applications of the continuous media data objects.