ITR/SY: Blurring the Line between OSes and Storage Devices

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

Disk systems have long been a source of performance and management problems, and they grow in importance as the years pass. Of particular concern are the slow-to-improve mechanical positioning delays. To address these problems, storage devices and host systems have abundant resources and knowledge. Independently, engineers of both device firmware and operating system (OS) software aggressively utilize their local knowledge and resources to mitigate disk performance problems. The overall goal of this research is to increase the cooperation between these two sets of engineers, which will increase the end-to-end performance and robustness of computer systems. This research will develop a deep understanding of available device and workload information and how it can be collectively exploited. Exploiting this understanding in real systems will require more expressive interfaces and new cooperative algorithms. Two concrete examples to be explored are: (1) device-side specializations, such as freeblock scheduling, that have access to system-provided information about priority levels and forthcoming demands, and (2) OS-side specializations, such as track-aligned extents, that have access to device-provided details about physical data layout and firmware cache algorithms. In addition, the insights generated by this research will assist end-to-end education and thinking in storage systems.