KVSSD：结合 LSM 与 FTL 以实现写入优化 的 KV 存储｜DB Paper Reading 线上直播

Content：

这篇 Paper 主要思路是 SSD 上直接提供 KV 接口，将 LSM Tree 与 FTL 深度结合，从而避免从 LSM Tree，主机文件系统到 FTL 多个软件层的写入放大。

Log-Structured-Merge (LSM) trees are a write-optimized data structure for lightweight, high-performance Key-Value (KV) store. Solid State Disks (SSDs) provide acceleration of KV operations on LSM trees. However, this hierarchical design involves multiple software layers, including the LSM tree, host file system, and Flash Translation Layer (FTL), causing cascading write amplifications. We propose KVSSD, a close integration of LSM trees and the FTL, to manage write amplifications from different layers. KVSSD exploits the FTL mapping mechanism to implement copy-free compaction of LSM trees, and it enables direct data allocation in flash memory for efficient garbage collection. In our experiments, compared to the hierarchical design, our KVSSD reduced the write amplification by 88% and improved the throughput by 347%.