Adaptive workload shaping for power savings on disk drives (abstracts only)

In order to reduce the amount of power consumption in data centers, it is becoming necessary to shut off or slow down disks that are not actively serving user requests. In addition to exploiting disk drive idleness, system features are in place that shape a disk's workload by redirecting portions of it elsewhere, with the goal to expand the periods of idleness and the potential for power savings. In this paper, we propose several workload shaping techniques that determine which part of the working set to copy elsewhere using temporal and spatial access frequencies in the workload. These workload shaping techniques, used within an analytic estimation methodology, enable a fully automated framework that determines on-line for the current workload which, if any, shaping technique to activate such that the power saving benefits are maximized without violating performance targets. Extensive trace-driven evaluation shows that the proposed workload shaping techniques complement each-other with regard to their abilities to enhance idleness in disk drives for a wide range of workload characteristics. This results to added power savings in a data center even when performance targets are stringent and workloads intensive.