一种基于网格的跨集群VOD系统及其仿真实现

提出了一种城域范围内基于网格技术的跨集群异构VOD系统实现框架；描述了系统硬件拓扑、软件层次结构，系统主要组件的交互活动．提出了一种对点播任务的分布式自适应调度算法并给出了基于此调度算法的仿真方案和结果．调度算法基于多目标规划，分为二级实现，包括任务在跨集群间的调度和集群内的调度．仿真结果显示，在系统的负载容量内，负载的大幅增加不会引起服务质量的显著下降。

A Grid-based VOD System and Its Simulation

Based on the GRID technologies, the authors suggest an implementation framework of a prospective grid VOD system which includes several hybrid clusters widely distributed within a metropolis. The hardware topology, the software structure and interactions among the main components of the system are described. A distributed adapting scheduler for the incoming VOD tasks is also suggested and simulated. The scheduler is divided into two parts, i.e.,a global part which distribute the tasks among individual clusters and a local part which works within a single cluster. The global part is designed based on multi-objective programming. Simulation shows that the scheduler works well even the system load increases by a big margin.