Hewlett-Packard Company

Manu Thapar

Shenze Chen

Christopher R Adams

Paolo L Siccardo

Albert W Kovalick

John J Youden

Kari A Santos

David John Coggins

James E Jensen

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. The video server is tolerant of individual failures in the data storage system and among the data sources, as operating portions of the data storage system and spare data sources can be rapidly switched to substitute for failed units. The server can also be readily expanded and provides a user experience similar to that of a video cassette recorder.

Video on demand system with multiple data sources configured to provide

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.

Deadline driven disk scheduler method and apparatus with thresholded

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. In a third embodiment, the highest rated video program in the hierarchy is located in a zone somewhat inwardly from the radially outermost zone, again attempting to provide a grouping that reduces seek time. In a last embodiment, the highest rated video programs in the hierarchy are recorded in the outermost zone, but the remaining video programs are recorded in a random fashion. This last embodiment trades some of the high bandwidth benefit at outer zones for the benefit of ease of implementation.

Zone bit recording enhanced video data layout

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.

Digital layout method suitable for near video on demand system

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.

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Fremont, CA, United States of America

Manu Thapar