Chihyun Lee  Sungho Moon  Sangeun Chae  Beomsuk Nam

10.5626/JOK.2025.52.11.1002

LSM-tree Key-Value Separated LSM-Tree compaction write stall ZNS-SSD

The LSM-Tree(Log-Structured Merge-Tree) is a widely adopted indexing structure known for its superior write performance across various application domains. However, a persistent performance bottleneck arises from write stalls caused by the relatively slow compaction process compared to the high rate of incoming data. Numerous studies, such as Key-Value Separated LSM-Tree and ZenFS, have been proposed to address this issue. In this paper, we introduce a method that replaces the LSM-Tree’s underlying file system with a ZNS-SSD (Zoned Namespace SSD) and leverages the simple copy to separate keys and values. This approach minimizes value-reading I/O from the disk while avoiding side effects like garbage collection, thereby accelerating the compaction process. We apply this technique to L0–L1 compaction and L0 compaction, effectively mitigating the write stall problem.