Boosting ZNS SSD Write Performance with Zora

Zoned Namespace (ZNS) SSD presents a new class of storage devices that offers low cost, high and consistent performance, and software definability. Nevertheless, ZNS demands strict sequential writing within a zone, which severely limits the write performance of small-sized requests. Unfortunately, existing solutions are all sub-optimal due to unsatisfactory write performance, the need for invasive host software modifications, and/or compromised read performance. In this paper, we propose Zora , a host-SSD collaborative framework, to fully address the write performance limitation for ZNS SSDs. Zora includes two core components: a zone area abstraction tailored for generic writes and a request admission control module located in the Linux block layer. They collaborate to boost ZNS SSD write performance to near-optimal (i.e., up to 94.1% in raw SSD access, up to 96.2% in filesystem workloads, and 24.2% to 48.5% in applications such as Varmail, OLTP, and SQLite), while benefiting upper-level applications and filesystems with full transparency.