Upgrading Service Capacity of Playback Servers with Buffer Caches

In this paper, we propose a new approach to exploit buffer caches to upgrade the service capacity of a multimedia on-demand playback system. The basic idea behind exploiting buffer caches 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 costs of memory chips continue 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 instances that the system can serve during a period of time by up to 124% and an average of 86% 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 7.0%.