Starlight Networks, Inc.

Joseph W Pang

Fouad A Tobagi

Joseph M Gang, Jr

Randall B Baird

Martin J McFadden

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 W.sub.base 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 W.sub.base bits/sec. One I/O transaction is performed for each stream in each of a plurality of I/O cycles of duration S/W.sub.base, 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/W.sub.base. More generally, when a stream has a bit rate (A/B)W.sub.base 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/W.sub.base. If the number of disks is N.sub.d, N.sub.d, .ltoreq.1, then the I/O cycles have a duration N.sub.d S/W.sub.base and then A I/O transactions are performed in each disk for each stream in B I/O cycles.

Method for scheduling I/O transactions for a data storage system to

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 W.sub.base 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 W.sub.base bits/sec. One I/O transaction is performed for each stream in each of a plurality of I/O cycles of duration S/W.sub.base, 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/W.sub.base. More generally, when a stream has a bit rate (A/B)W.sub.base 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/W.sub.base. If the number of disks is N.sub.d,N.sub.d .gtoreq.1, then the I/O cycles have a duration N.sub.d S/W.sub.base and then A I/O transactions are performed in each disk for each stream in B I/O cycles.

Method for scheduling I/O transactions in a data storage system to

A method for increasing the storage capacity of a video server which utilizes an array of disks is disclosed. The server is operated so that the continuity of a plurality of bit streams is maintained. The inventive method has advantageous characteristics with respect to storage capacity, streaming capacity, start-up latency of new streams, amount of required buffer capacity, scalability, reliability and multiple bit rates.

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Fremont, CA, United States of America

Joseph W Pang