Braid-ZNS: Leveraging Zone Random Write Area for Efficient In-Storage Compression on ZNS SSDs

Zoned Namespace (ZNS) SSD is an emerging storage solution that reduces device-level garbage collection and write amplification. However, the sequential write constraint of ZNS SSDs poses a challenge to adopting in-storage compression, as data placement rules prevent compressed variable-length data from being packed into optimally sized chunks. In this paper, we propose Braid-ZNS, a novel in-storage compression framework that leverages the Zone Random Write Area (ZRWA) to avoid double reads during data compression on ZNS SSDs. By exploiting the ZRWA to enable temporary in-place updates, Braid-ZNS reorganizes compressed blocks in a size-aware manner and prevents cases where a single logical page is split into multiple fragments. Our evaluation shows Braid-ZNS improved compression efficiency by up to 47.0% and throughput by ×2.24 compared to a state-of-the-art in-storage compression on ZNS SSDs.