Load Management in Distributed Video Servers

In this paper, we define and formulate various policies for load management in distributed video servers. We propose a predictive placement policy that determines the degree of replication necessary for popular videos using a cost-based optimization procedure based on a priori predictions of expected subscriber requests. For scheduling requests, we propose an adaptive scheduling policy that compares the relative utilization of resources in a video server to determine an assignment of requests to replicas. To optimize storage utilization, we also devise methods for dereplication of videos based on changes in their popularities and in server usage patterns. Performance evaluations indicate that a load management procedure which uses a judicious combination of the diflerent policies performs best for most server configurations. Advances in storage technologies are making highperformance video servers a reality. These video servers are being deployed over emerging broadband networks to deliver a variety of interactive, digital video services to thousands of residential subscribers. To meet the scalability requirements in such large deployments, distributed video server architectures are being considered [3]. In this paper, we propose various methods for load management that are targeted at improving the cost-effectiveness of distributed video servers. The paper is organized as follows: Section 1 motivates the need for load management and discusses its implications on a video server’s cost-performance. Section 2 presents the different policies for load management while Section 3 discusses more optimizations for load management. Section 4 presents a comparative analysis of the different policies. We conclude in Section 5 and outline areas for future research. 1 Load Management in Video Servers Figure 1 illustrates the architecture of a typical video server, the main components of which are: a number of independent and distributed data sources, each of which includes high capacity storage devices, ? . --< Distribution Network