Exploring Performance Characteristics of ZNS SSDs: Observation and Implication

ZNS SSDs (Zoned NameSpace Solid State Drives) are a new type of SSD that provides various features such as zone concept and host-level flash management. In this paper, we explore how these features affect performance characteristics of ZNS SSDs. To this end, we design an analysis tool based on a real ZNS SSD prototype that allows to evaluate performance under different workloads. Then, we investigate diverse characteristics in terms of parallelism, isolation and predictability. Our observations reveal that 1) requesting I/Os in a large unit is indispensable in ZNS SSDs to obtain parallelism, 2) workloads can be isolated more effectively compared with traditional SSDs, 3) unexpected performance drop is not monitored, and 4) performance differs based on LBAs (Logical Block Addresses), which can be exploited usefully when we devise a new algorithm for ZNS SSDs.