Random duplicated assignment: an alternative to striping in video servers

Abstract

An approach is presented for storing video data in large disk arrays. Video data is stored by assigning a number of copies of each data block to different, randomly chosen disks, where the number of copies may depend on the popularity of the corresponding video data. The approach offers an interesting alternative to the well-known striping techniques. Its use results in smaller response times and lower disk and RAM costs if many continuous variablerate data streams have to be sustained simultaneously. It also offers some practical advantages relating to reliability and extendability. Based on this storage approach, three retrieval algorithms are presented that determine, for a given batch of data blocks, from which disk each of the data blocks should be retrieved. The performance of these algorithms is evaluated from an average-case as well as a worst-case perspective. key words: video serve< striping, disk array, RAID, multimedia, variable rate