SCMKV: A Lightweight Log-Structured Key-Value Store on SCM

Storage Class Memories (SCMs) are promising technologies that would change the future of storage, with many attractive capabilities such as byte addressability, low latency and persistence. Existing keyvalue stores proposed for block devices use SCMs as block devices, which conceal the performance that SCMs provide. A few existing key-value stores for SCMs fail to provide consistency when hardware supports such as cache flush on power failure are unavailable. In this paper, we present a key-value store called SCMKV that provides consistency, performance and scalability. It takes advantage of characteristics of key-value workloads and leverages the log-structured technique for high throughput. In particular, we propose a static concurrent cache-friendly hash table to accelerate accesses to key-value objects, and maintain separate data logs and memory allocators for each worker thread for achieving high concurrency. To reduce write latency, it tries to reduce writes to SCMs and cache flushing instructions. Our experiments show that SCMKV achieves much higher throughput and has better scalability than state-of-the-art key-value stores.