Parallel-Log-Single-Compaction-Tree: Flash-Friendly Two-Level Key-Value Management in KVSSDs

Abstract

Log-Structured Merge-Tree (LSM-tree) based key-value store applications have gained popularity due to their high write performance. To further pursue better performance for key-value applications, various researches were conducted by adopting different architectures of flash devices, such as key-value solid-state drives (KVSSDs). However, since LSM-trees were originally designed based on the architecture of hard disk drives (HDDs), true potential of SSDs can not be well exploited without re-designing the management strategy. In this work, we propose Parallel-Log-Single-Compaction-Tree (PLSC-tree), which is a two-level and flash-friendly key-value management strategy specially tailored for KVSSDs. In particular, the first layer takes advantage of the massive internal parallelism of SSDs for maximizing the write performance via logging, while the second layer is designed to alleviate the internal recycling (i.e., compaction) overheads of flash devices for ultimately optimizing the performance on managing key-value pairs. A series of experiments were conducted based on a well-known SSD simulator with realistic workloads, and the results are very encouraging.