Dynamic Load Balancing Method Based on DNS for Distributed Web Systems

摘要

In most existing distributed Web systems, incoming requests are distributed to servers via Domain Name System (DNS). Although such systems are simple to implement, the address caching mechanism easily results in load unbalancing among servers. Moreover, modification of the DNS is necessary to load balancing considering the server's state. In this paper, we propose a new dynamic load balancing method using dynamic DNS update and round-robin mechanism. The proposed method performs effective load balancing without modification of the DNS. In this method, a server is dynamically added to or removed from the DNS list according to the server's load. By removing the overloaded servers from the DNS list, the response time becomes faster. For dynamic scheduling, the scheduling algorithm consider usage rates of servers' three main resources-CPU, memory, and network. We also implement a GUI-based management tool to manage the system across the network. Experiments show that modules implemented in this paper have a low impact on performance of the proposed system. Furthermore, experiments show that both the response time and the average file transfer rate of the proposed system are faster than those of a pure Round-Robin DNS.