Dynamic real-time scheduling strategies for interactive continuous media servers

In this paper, we propose and study a dynamic approach to schedule real-tim e requests in a video-on-demand (VOD) server. Providing quality of service in such servers requires uninterrupted and on-time retrieval of motion vide o data. VOD services and multimedia applications further require access to the storage devices to be shared among multiple concurrent streams. Most of the previous VOD scheduling approaches use limited run-time,0 information and thus cannot exploit the potential capacity of the system fully. Our app roach improves throughput by making use of run-time information to relax ad mission control. It maintains excellent quality of service under varying pl ayout rates by observing deadlines and by reallocating resources to guarant ee continuous service. It also reduces start-up latency by beginning servic e as soon as it is detected that deadlines of all real-time requests will b e met. We establish safe conditions for greedy admission, dynamic control o f disk read sizes, fast initial service, and sporadic services, We conduct thorough simulations over a wide range of buffer capacities, load settings, and over varying playout rates to demonstrate the significant improvements in quality of service, throughput and start-up latency of our approach rel ative to a static approach.