Dotori: A Key-Value SSD Based KV Store

Abstract

Key-value SSDs (KVSSDs) represent a major shift in the storage stack design, with numerous potential benefits. Despite this, their lack of native features critical to operation in real world scenarios hinders their adoption, and these benefits go unrealized. Moreover, simply adapting existing key-value stores to run on KVSSDs proves underwhelming, as KVSSDs operate at lower raw device performance when compared to modern block SSDs. This paper introduces Dotori. Dotori is a KVSSD based key-value store that provides much needed functionality in a KVSSD through an upper layer in the host, and takes advantage of the unique KVSSD interface to enable further gains in functionality and performance. At the core of Dotori is a novel B+tree design that is only practical when the underlying storage device is a KVSSD. We test Dotori with an enterprise grade KVSSD against state-of-the-art block SSD based key-value stores through a range of micro-benchmarks and real world workloads. Despite low KVSSD raw device performance, Dotori achieves superior performance to these block-device based key-value stores while also showing significant gains in other important metrics.