A Redundant Hierachical Structure for a Distributed Continuous Media Server

The growing number of digital audio and video repositories has resulted in a desperate need for eeective techniques to deliver data to users in a timely manner. Due to geographical distribution of users, it is not cost eeective to have a centralized media server. In this paper, we investigate issues involved in the design of a distributed video server (DVS) to support movie-on-demand (MOD) application. We propose a redundant hierarchical (RedHi) architecture for DVS where the nodes are continuous media servers and the edges are dedicated network lines. With RedHi, each node has two or more parents. We show that the redundant links in RedHi yield a more reliable and eecient system. Our simulation results demonstrate that RedHi can tolerate a single link failure with no degradation in performance while with pure hierarchy almost 2:5% of requests are rejected due to the failure. In normal mode of operation, RedHi outperforms pure hierarchy signiicantly (160% improvement on the average when counting the number of rejections). In the context of RedHi, we also propose and evaluate alternative object management policies, and load balancing heuristics.