Improving reliability of distributed VoD servers

VoD services (video on demand) are characterized by QoS (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; the reliability and the 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 disk, and do not integrate the consequence of CPU failures. To deal with this issue, the authors have previously proposed a resource reservation model that integrates reliability requirements. They 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 available-resource manager implements a load balancing strategy which provides reliability on demand and guarantees the server´s accessibility. The paper detail the corresponding algorithm and presents results proving that their load balancing strategy reduces the cost of reliability in terms of resource consumption