Method for scheduling I/O transactions for a data storage system to maintain continuity of a plurality of full motion video streams

摘要

A method for operating a disk storage system, comprising a disk and forming part of a communications network, simultaneously maintains the continuity of a plurality of data streams. Typically, each stream transfers video data to or from the disk storage system. Illustratively, each of the data streams is produced in the network at a rate of Wbase bits/sec and consumed by the disk storage system or produced by said disk storage system and consumed in the network at a rate of Wbase bits/sec. One I/O transaction is performed for each stream in each of a plurality of I/O cycles of duration S/Wbase, wherein in each I/O transaction a segment of S bits is retrieved from or stored in the disk. The number of streams whose continuity can be maintained in this manner is limited by the number of I/O's which can be performed in a cycle of duration S/Wbase. More generally, when a stream has a bit rate (A/B)Wbase bits/sec where A and B are integers chosen independently for each stream, then for this-stream A I/O transactions are performed in B cycles of duration S/Wbase. If the number of disks is Nd, Nd,