Power-saving Design in Server Farms for Multi-tier Applications under Response Time Constraint

Server farms suffer from an increasing power consumption nowadays. Power saving has become a prominent design issue in server farms. This paper presents a power-saving design in server farms under the constraint of the response time. In particular, we target on multi-tier applications, which are very typical on the web in modern days. We propose an efficient power-saving design strategy, called PowerTier. This strategy exploits two major techniques by using Dynamic Power management (DPM) to activate/deactivate servers and using Dynamic Voltage Scaling (DVS) to adjust the processor speed for each activated server. In addition, PowerTier considers two different application models: the open-queueing model and the closed-queueing model for session-less and session-based web applications respectively. With PowerTier, we are able to choose the number of activated servers at each tier and the processor speed for each server to minimize the overall power consumption in server farms while meeting a given mean response time guarantee for multi-tier applications. Our comprehensive simulation confirms the effectiveness and efficiency of PowerTier.