A Study of Memory Management in Video-on-Demand Systems

This paper presents a study on exploiting semiconductor memory to upgrade the service capacity of video on-demand playback systems. The basic idea behind exploiting semiconductor memory is that, if we can relay the data of highly frequently accessed programmes from one access request to another, then we can upgrade the service capacity of the system without requiring higher disk bandwidth. As the price/bit metric of semiconductor memory continues to drop at a fast pace, the future trend apparently favors implementation of the relaying mechanism. The simulation-based study shows that, for short programmes such as cartoons or songs, the relaying mechanism can increase the number of access requests that the system serves during a period of time by up to 113% with an average of 80% without installing more disks. Meanwhile, the average rejection rate observed by the clients, i.e. the rate that access requests are rejected by the system due to limited capacity, drops from 60.4% to 13%.