Hi-ZNS: High Space Efficiency and Zero-Copy LSM-Tree Based Stores on ZNS SSDs
Renping Liu, Junhua Chen, Peng Chen, Linbo Long, Anping Xiong, Duo Liu · 2024
The Zoned Namespace (ZNS) SSD is a newly introduced storage device and provides several new ZNS commands to upper-level applications. Zone-reset command is one of the ZNS commands to erase all the flash blocks within a zone. Since data is grouped and erased in zone units, ZNS SSDs are widely used in LSM-tree-based stores. However, the basic invalidated unit in LSM-tree is an SST/WAL file, which mismatches the erasing unit of a ZNS SSD. Placing different SST/WAL files in the same zone, LSM-tree on ZNS SSDs faces dramatic space amplification and extensive data migration problems.