Centralized versus distributed multimedia servers

The organization of multimedia servers is important in the design of low-cost high-performance multimedia application environments. Considering video services as highly demanding applications in a multimedia environment, we analyze and compare centralized and distributed architectures for multimedia video servers. Comparisons are made in terms of the blocking probability of a video clients request, considering as important parameters the input/output capacity of the system and the amount of storage. Through a combination of analytical results and simulations, we conclude that in general a centralized architecture is preferable. The results indicate, however, that in a distributed architecture containing a large number of powerful servers, performance is similar to the centralized architecture under high load conditions, while the blocking probabilities are quite small under light load conditions. Furthermore, centralized and distributed server architectures become equivalent when large amounts of storage are added to the latter or when their input/output capacity is significantly increased. The results indicate that in many practical environments, factors other than performance, such as cost of management, security, and fault tolerance, will influence the choice for the appropriate server configuration.