This paper provides a data placement method based on rate staggering to store scalable video data in a disk-array-based video server. A scalable, or layered, video stream is one which is encoded in a manner that permits the extraction of lower resolution subsets from the full- resolution video bit stream. It is desirable to support layered video streams from a video server since these can be used to serve a variety of clients with different decoding capabilities. When a layered video stream is stored on a disk array, the video data corresponding to different rates of the video clip are not required to reside in the same disk. In view of this, we propose and explore the approach of rate staggering, i.e., staggering video data in the disk array based on data rates. It is shown that the advantages of the proposed rate staggering method include: (1) minimizing the intermediate buffer space required at the server, (2) achieving better load balancing due to finer scheduling granularity, and (3) alleviating the disk bandwidth fragmentation. These advantages enable a video server using the rate staggering method to provide feasible solutions to some video stream requests which cannot be met otherwise. The system throughput can thus be increased.
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