Several solutions have been proposed till date to achieve effective replication policies and admission control methods that can ensure a high Quality of Service (QoS) to Video on Demand (VoD) systems. In this paper, we have chosen to study admission control and a replication strategy in a video on demand system called Feedback Control Architecture for Distributed Multimedia Systems (FCA-DMS). The proposed approaches are founded on (i) the supervision and auto-adaptation of the system load, (ii) continued knowledge of the network and of the video servers’ workload, and (iii) the development of a dynamic replication strategy of segments for popular video, that remade to replica-placement problem by discussing the problem of the replicas number to create (Replication Degree). The workload of video servers and of network are calculated by a QoS controller. The proposed approach takes into account of replica detail and offers a replica removal policy to avoid waste and for a good management of storage space. The goal is to maintain an updated broad view of the system’s behaviour from the collected measurements to databases of available videos and databases of available video servers. To demonstrate the efficiency and feasibility of our approaches and validate the results obtained, we conducted a series of experiments based on a simulator that we implemented. 
Effect of selective replication strategy and dynamic admission control to QoS management in video on demand systems