Providing Reliability on Demand in Distributed VoD Servers

Video on Demand (VoD) services are characterized by quality of service requirements which depend on: the quality of video and sound transmitted to the client, the respect of time constraints associated to video and audio data and the reliability and accessibility of the service. Much work has been done in order to provide system support aimed at meeting reliability requirements in distributed VoD servers. However, existing proposals focus on the treatment of failures of the network and disks, and do not integrate the consequence of CPU failures. To deal with this issue, we propose a resource reservation model that integrates reliability requirements. In this paper, we customize the resource manager of a distributed VoD server in order to take advantage of the large set of resources (disks and CPUs) to enhance the server’s reliability. The proposed resource manager implements a load balancing strategy which provides reliability on demand and guarantees the server’s accessibility. This paper details the design and implementation of the corresponding algorithm, and presents results showing that our load balancing strategy reduces the cost of reliability in terms of resource consumption. Key-words: reliability, quality of service, distributed system, video on demand, resource reservation, fault-tolerance