Scalable and fault-tolerant support for variable bit-rate data in the exedra streaming server

Abstract

We describe the design and implementation of the Exedra continuous media server, and experimentally evaluate alternative resource management policies using a prototype system that we built. Exedra has been designed to provide scalable and efficient support for variable bit-rate media streams whose compression efficiency leads to reduced storage space and bandwidth requirements in comparison to constant bit-rate streams of equivalent quality. We examine alternative disk striping policies, and quantify the benefits of innovative techniques for storage space allocation, buffer management, and resource reservation, which we developed to achieve both predictability and high-performance in handling disk and network data transfers of variable size. Additionally, we investigate the differences between diverse data replication schemes over disk arrays, and compare methods for disk access time reservation that enable tolerance of disk failures at minimal cost. Overall, we demonstrate the feasibility of building network media servers that exploit the latest advances in media compression technology towards reducing the cost of wide-scale streaming services for stored data.