에너지 절감형 서버 클러스터에서 급변하는 부하 처리를 위한 유연한 다중 임계치 기반의 서버 전원 모드 제어

Abstract

Energy aware server cluster aims to reduce power consumption at maximum while keeping QoS(quality of service) as much as energynon-aware server cluster. In the existing methods of energy aware server cluster, they calculate the minimum number of active serversneeded to handle current user requests and control server power mode in a fixed time interval to make only the needed servers ON. When loads change rapidly, QoS of the existing methods become degraded because they cannot increase the number of active servers soquickly. To solve this QoS problem, we classify load change situations into five types of rapid growth, growth, normal, decline, and rapiddecline, and apply five different thresholds respectively in calculating the number of active servers. Also, we use a flexible scheme toadjust the above classification criterion for multi threshold, considering not only load change but also the remaining capacity of servers tohandle user requests. We performed experiments with a cluster of 15 servers. A special benchmarking tool called SPECweb was used to generate loadpatterns with rapid change. Experimental results showed that QoS of the proposed method is improved up to the level of energynon-aware server cluster and power consumption is reduced up to about 50 percent, depending on the load pattern.