Video database techniques and video-on-demand

Generally, a large-scale video server is composed of numerous disk striping groups. The striping policies employed by each disk striping group largely determine the performance of a video server. For storage and transmission efficiency, video data are usually compressed using variable-bit-rate (VBR) encoding algorithms, such as JPEG and MPEG. The amount of data consumed by a VBR video stream varies with time. This property, when coupled with striping, unfortunately, results in load imbalance across disks, degrading the overall server performance significantly. This chapter focuses on VBR video striping. It presents two state-of-the-art VBR striping schemes proposed in the literature: one is designed for homogeneous disks and the other is designed for heterogeneous disks. To gain insights into VBR striping, this chapter also develops performance models for the two striping policies. With these performance models, system designers can predict the maximum service capacity of a server, perform online admission control for clients, and optimize the performance of a server, without performing exhaustive tests on a real system.