Minimizing Power Consumption with Performance Efficiency Constraint in Web Server Clusters

Energy efficiency has become a very important issue to reduce the consumption of resources on the Earth. We have to consider how to save the energy consumption anywhere and anytime, including a large set of servers, for example, servers in the Google company. Hence, power and energy consumption has recently become key concerns, especially huge number of servers are deployed in large cluster configurations as in data centers and Web hosting facilities. Even though we emphasize power saving as much as possible, the performance of servers should be ensured. So far, there have been some discussions about enhancing power conservation. However, with the best of our knowledge, a mathematical model about consumed power and server´s performance has not been discussed. Therefore, in this paper, we attempted to minimize the energy consumption with performance constraint of web servers. We know, the response time is the focus of the performance in web servers. Therefore, we first find the trade off value of load for each server based on optimized methods. With the trade off load, the performance of users can be satisfied at the same time the power consumption is minimized. Then, using the trade off load value, we propose a novel load allocation method and then discuss the effectiveness of our load allocation method by comparing with other two methods: random load allocation method and average load allocation method.