This paper discusses several practical issues related to the provision of video-on-demand (VOD) services, focusing on retrieval of video data from disk on the server. First, with regard to system design, the pros and cons of cycle-based scheduling algorithms for VOD servers are compared, and an adequate policy according to system configuration is presented. Second, we present a way to tune the cycle-based scheduling algorithm so that it maximizes profit. Third, a method to overcome the cons of cycle-based scheduling algorithms is proposed, and its cost is analyzed.

Storage system in a multimedia server must satisfy two contradicting requirements: real-timeliness and large number of parallel user requests. Efficient algorithms for data placement, disk head scheduling, and request admission control schemes are needed to support the requirements. In this paper, we propose efficient schemes to maximize system resource utilization and service availability: cyclic placement scheme, subgroup retrieval scheme, and measurement-based request admission control scheme. Performance analysis through simulation revealed that the amount of system buffers required can be reduced by 70% approximately.