GAP: A Global Wear-Aware Block Pool for Enhancing Lifetime of ZNS SSDs
Renping Liu, Cheng Ran, Han Hu, Anping Xiong, Peng Chen, Linbo Long · 2024
The Zoned Namespace (ZNS) interface shifts the responsibility of data management to the host. However, host software tends to ignore or even fails to guarantee the wear-leveling of zones due to a lack of semantics. In this paper, we propose GAP, a device-level dynamic zone construction policy to ensure wear-leveling and enhance the lifetime of ZNS SSDs. The key idea of GAP is to break up all flash blocks within a ZNS SSD device to form a block pool. Once a zone's wear degree reaches a threshold, GAP selects the right number of flash blocks from the block pool to reconstruct the zone for the wear-leveling purpose. Experimental results based on the NVMe ZNS SSD emulator (FEMU) show that GAP outperforms the existing policy by 14.4x over ZenFS and RocksDB.