Abstract

Pelican is a rack-scale design for cheap storage of data which is rarely accessed: cold data. It uses spun-down hard drives to maximise density and reduce costs. A Pelican rack supplies only enough resources (power, cooling, bandwidth) to support the cold data workloads we target, significantly reducing Pelican’s total cost of ownership compared to traditional disk-based systems provisioned for peak performance. The Pelican storage stack manages the limited resources, and their constraints. We describe the data layout and IO scheduling algorithms which ensures these constraints are not violated, while making best use of the available resources. We evaluate Pelican both in simulation and with a full rack, and show that Pelican performs well: delivering both high throughput and acceptable latency.

Bio: Austin Donnelly is a Principal Research Software Development Engineer (RSDE) in the Systems group at Microsoft Research, Cambridge. He obtained his B.A. in Computer Science from the University of Cambridge in 1996, and went on to complete his Ph.D. there in 2002. He has worked on storage technologies for around 20 years, from writing an IDE driver for Nemesis (a research OS), to research on the write-offloading technique used in DiskEnergy to save power. He is currently working on the Pelican system for cold storage in datacentre environments.