The central point of this paper is that energy should be viewed as an important element of resource management for Web sites, hosting centers, and other Internet server clusters. In particular, we are developing a system to manage server resources so that cluster power demand scales with request throughput. This can yield significant energy savings because server clusters are sized for peak load, while traces show that traffic varies by factors of 3-6 or more through any day or week, with average load often less than 50% of peak. We propose energy-conscious service provisioning, in which the system continuously monitors load and adaptively provisions server capacity. This promises both economic and environmental benefits.

Internet hosting centers serve multiple service sites from a common hardware base. This paper presents the design and implementation of an architecture for resource management in a hosting center operating system, with an emphasis on energy as a driving resource management issue for large server clusters. The goals are to provision server resources for co-hosted services in a way that automatically adapts to offered load, improve the energy efficiency of server clusters by dynamically resizing the active server set, and respond to power supply disruptions or thermal events by degrading service in accordance with negotiated Service Level Agreements (SLAs).Our system is based on an economic approach to managing shared server resources, in which services "bid" for resources as a function of delivered performance. The system continuously monitors load and plans resource allotments by estimating the value of their effects on service performance. A greedy resource allocation algorithm adjusts resource prices to balance supply and demand, allocating resources to their most efficient use. A reconfigurable server switching infrastructure directs request traffic to the servers assigned to each service. Experimental results from a prototype confirm that the system adapts to offered load and resource availability, and can reduce server energy usage by 29% or more for a typical Web workload.