Scalable Services for Video-on-demand

Video-on-demand (VOD) refers to video services in which users can request any video program from a server at any time. VOD has important applications in entertainment, education, information, and adverstising, such as movie-on-demand, distance learning, home shopping, interactive news, etc. In order to provide VOD services accommodating a large number of video titles and concurrent users, a VOD system has to be scalable | scalable in storage and scalable in streaming capacity. Our goal is to design such a system with low cost, low complexity, and o ering high level of service quality (in terms of, for example, user delay experienced or user loss rate). Storage scalability is achieved by using a hierarchical storage system, in which video les are stored in tertiary libraries or jukeboxes and transferred to a secondary level (of magnetic or optical disks) for display. We address the design of such a system by specifying the required architectural parameters (the bandwidth and storage capacity in each level) and operational procedures (such as request scheduling and le replacement schemes) in order to meet certain performance goals.