Valet: Efficient Data Placement on Modern SSDs

Abstract

Valet leverages userspace shim layers to add placement hints for application data, delivering up to 2-4x write throughput over filesystems and comparable or better performance than application-specific solutions, with up to 6x lower tail latency. Valet generates dynamic placement hints, remapping application data to modern SSDs with zero modifications to the application, the filesystem, or the kernel. To the authors' knowledge, this is the first work to present a generalized theory of data placement, showcasing affinity and lifetime as the important parameters over temperature-based approaches of the past. Valet is fast: achieving 2-6 times higher write throughput, up to 6 times lower latency, and reduced garbage overhead over filesystems and application backends.