An Analytical Model of Web Server Load Distribution by Applying a Minimum Entropy Strategy

Abstract

 Abstract—This paper presents an analytical model and the way of simulation for distributing workload on a distributed web server system. The increase in the Internet traffic has also necessitated the conventional Domain Naming Service (DNS) to operate at a much lower efficiency. Among a number of problems associated with the DNS, a key problem has to do with the authoritative DNS not being able to process complete knowledge of the proximity. This makes the authoritative DNS less effective in monitoring server availability and routing incoming requests around failed servers. The workload distribution strategy on the other hand, keeps track of the state and health of the web server. This avoids connection delay due to, for example, a failed server, which can be temporarily by passed by workload distribution. From a modeling standpoint, the conventional DNS assumes equal queue size for each web server in a round-robin setting. Under load balancing, the queue size for each web server differs based on the probability of accessing that server. This probability is based on such factors as the geography, server health, server response, server threshold, session capacities, and the round trip time. In this paper, both conventional and global workload distribution strategies are developed and compared based on a finite set of practical traffic scenarios.