Pipelined disk arrays for digital movie retrieval

Abstract

We develop a reliable disk array based storage architecture for digital video retrieval. Our goals are two fold: maximizing the number of concurrent real time sessions while minimizing the buffering requirements, and ensuring a high degree of reliability. The first goal is achieved by adopting a pipelined approach and by reducing latencies through specialized disk caching and constrained data placement schemes. The second goal is achieved by dividing the disks into RAID 3 reliability groups which serve as pipeline stages. We note that the buffering requirement decreases as the number of groups increases. To improve the performance further, we introduce two techniques for more efficient movie retrieval: on arrival caching, and interleaved annular layout. We present a case study of the performance of these techniques which shows a significant improvement when they are incorporated.