LAUSR

As big data applications proliferate, datacenters today are increasingly looking to adopt a scale-out model. Nevertheless, power capacity has become an important bottleneck that restricts horizontal scaling of servers, especially in datacenters that oversubscribe power infrastructure. When a datacenter hits its ceiling for power provisioning, conventionally the owner has to either build another facility or upgrade existing infrastructure—both approaches add huge cost, require significant time, and can further increase carbon footprint. This paper proposes Oasis, a novel datacenter expansion strategy that enables power-/carbon- constrained servers to scale out economically and sustainably. The basic structure of Oasis, called Oasis Node, naturally supports incremental capacity expansion with near-zero environmental impact since it leverages modular solar panels and distributed battery systems to power newly added servers. To optimize the operation of newly added nodes, we further propose a management framework called Ozone. It allows Oasis to jointly perform power supply switching and server speed scaling to improve efficiency locally and globally. We implement a prototype of Oasis and use it as a research platform for evaluating the design tradeoffs of green scale-out datacenters. With Oasis, a green datacenter could gradually double its capacity with near-oracle performance, extended battery lifetime, and 26 percent cost savings.