Abstract: A packet mapper prioritizes streams of data packets in a computer network, each data packet having a packet header containing feature values descriptive of the data packet. The packet mapper includes a mapping table that associates application-related features with network-reserved feature values from a range of feature values reserved for use by selected network data packet streams, and a feature value mapper that performs at least one of (i) in each packet header having an application-related feature value associated with a network-reserved feature value, substituting the associated network-reserved feature value for the application-related feature value, and (ii) in each packet header having a network-reserved feature value associated with an application-related feature value, substituting the associated application-related feature value for the network-reserved feature value.

Abstract: A video server for providing Video-On-Demand is disclosed. A plurality of data sources are coupled individually to a first and second bi-directional data/instruction switch. The first switch is additionally coupled to a data storage system and the second switch is coupled to a network interface. A real time controller is coupled to the data sources and the switches and can couple any part of the data storage system to any selected data source and any given network channel to any selected data source. A control system coupled to the real time controller and the second switch provides support services to the real time controller and acts as a gateway to third party services and products. The data storage system is largely comprised of disk drive arrays. Video data is striped across the individual arrays, each video data program that a user requests being striped across one array. Each array provides video data to many users through the data sources.

Abstract: A disk control mechanism for controlling the operations of a movable arm disk drive. The disk control mechanism contains a disk access scheduler which accepts disk access requests having a deadline and a disk location. The disk access scheduler further consists of a queue data structure for storing the requests. The queue contains a predefinded window that contains a certain number of requests with deadlines to expire sooner than all other requests. The request that is most soon to expire, the most urgent request, is located at the head of the queue. The disk access scheduler contains logic to determine whether the most urgent request has a deadline to expire sooner than tolerated by a set threshold, and in such cases the disk access scheduler schedules for service the most urgent request prior to any other request, otherwise it scans towards the most urgent request and schedules requests with a disk location between the current arm location and the most urgent request.

Abstract: A method of storing video programs, such as movies, for video-on-demand access includes forming a hierarchy for the movies based upon anticipated frequencies of access. Typically, more than one magnetic disk is used to store the video programs, with each disk being partitioned into concentric annular zones. In one embodiment, there is a direct correspondence between the hierarchy and the assignment of video programs to the annular zones. The movies that are anticipated to have the highest frequency of video-on-demand access are placed in the radially outermost zone until it is filled. The next highest video program is then recorded in the next zone. This pattern is followed until the radially innermost zone is filled. In a second embodiment, the same pattern is followed, but with the movies within the outer zones being strategically located within those zones in order to potentially reduce seek time.

Abstract: A method for layout of digitized media, movies, especially on discs, whereby storage capacity and bandwidth are optimized and near video on demand is accomplished. Several embodiments are taught, including request stimulated near video on demand model which employs the inventive layout strategy taught.

Abstract: The present invention is an apparatus and method for using the dual port feature of Fibre Channel to allow multiple computer hosts to simultaneously access a cluster of memory units that are Fibre Channel arbitrated. Typical multiple host access schemes require an expensive Fibre Channel switch and do not allow simultaneous accessing. The dual port feature of Fibre Channel devices provides for fault tolerance and redundancy, but can be used for the present invention.

Abstract: A video server for providing Video-On-Demand is disclosed. A plurality of data sources are coupled individually to a first and second bi-directional data/instruction switch. The first switch is additionally coupled to a data storage system and the second switch is coupled to a network interface. A real time controller is coupled to the data sources and the switches and can couple any part of the data storage system to any selected data source and any given network channel to any selected data source. A control system coupled to the real time controller and the second switch provides support services to the real time controller and acts as a gateway to third party services and products. The data storage system is largely comprised of disk drive arrays. Video data is striped across the individual arrays, each video data program that a user requests being striped across one array. Each array provides video data to many users through the data sources.

Abstract: A fully densified, self-reinforced silicon nitride ceramic body of high fracture toughness and high fracture strength is disclosed comprising (a) .beta.-silicon nitride in the form of whiskers having an average aspect ratio of at least about 2.5, and (b) a crystalline grain boundary phase having an oxynitride apatite structure, as determined by X-ray crystallography.A process for preparing the above identified silicon nitride body comprising hot-pressing a powder mixture containing silicon nitride; silica; a densification aid including strontium oxide; a conversion aid, such as, yttrium oxide; and a compound, such as, calcium oxide which enhances growth of .beta.-silicon nitride whiskers, under conditions such that densification and the in situ formation of .beta.-silicon nitride whiskers having a high aspect ratio occur, and thereafter annealing the densified composition for a time sufficient to produce a crystalline grain boundary phase having an oxynitride apatite structure.