SleepServer: A Software-Only Approach for Reducing the Energy Consumption of PCs within Enterprise Environments

Desktop computers are an attractive focus for energy savings as they are both a substantial component of enterprise energy consumption and are frequently unused or otherwise idle. Indeed, past studies have shown large power savings if such machines could simply be powered down when not in use. Unfortunately, while contemporary hardware supports low power “sleep” modes of operation, their use in desktop PCs has been curtailed by application expectations of “always on” network connectivity. In this paper, we describe the architecture and implementation of SleepServer, a system that enables hosts to transition to such low-power sleep states while still maintaining their application’s expected network presence using an ondemand proxy server. Our approach is particularly informed by our focus on practical deployment and thus SleepServer is designed to be compatible with existing networking infrastructure, host hardware and operating systems. Using SleepServer does not require any hardware additions to the end hosts themselves, and can be supported purely by additional software running on the systems under management. We detail results from our experience in deploying SleepServer in a medium scale enterprise with a sample set of thirty machines instrumented to provide accurate real-time measurements of energy consumption. Our measurements show significant energy savings for PCs ranging from 60%-80%, depending on their use model.