QUEUING ARCHITECTURE WITH MULTIPLE QUEUES AND METHOD FOR STATISTICAL DISK SCHEDULING FOR VIDEO SERVERS

摘要

A queuing architecture and method for scheduling disk driveaccess requests in a video server. The queuing architecture employsat least two access request queues (221; 222, 223) for each diskdrive (120) within a disk drive array. A first queue (221) is for diskaccess requests by steady-state users currently viewing a program.A second queue, which may include multiple queues (222, 223),is for all other types of access requests including requests by userswho wish to begin viewing a program, disk maintenance, meta datasynchronizing and the like. A queue selector (205) gives highestpriority to requests in the first queue to maintain time deadlinesfor steady state disk access requests, which are serviced in order ofascending deadlines. Requests from the second queue are servicedonly if all of the steady-state requests in the first queue will meettheir time deadlines in the worst case.