Mjölnir: collecting trash in a demanding new world

Abstract

As flash devices become ubiquitous in data centers and cost per gigabyte drops, flash systems need to provide data services similar to those of traditional storage. We present Mjölnir, a powerful and scalable engine that addresses the core problems that make efficient flash based data services challenging: multi-reference management and garbage collection. Additionally, by providing powerful primitives for address remapping, Mjölnir enables redesign of the I/O stack for greater efficiency and performance with flash. Mjölnir uses techniques from language runtimes for reference management and garbage collection; we show via prototype and experimental evaluation that this design can deliver predictable performance even with varied user workloads across a range of capacity and reference-count scales.