ConZone+: Practical Zoned Flash Storage Emulation for Consumer Devices

TL;DR

ConZone addresses the gap in realistic emulation of consumer-grade zoned flash storage by modeling constrained write buffers, limited L2P caches, and hybrid mapping, which are critical for hardware/firmware and file-system optimization. The authors extend ConZone with ConZone+, adding a block-interface and multi-namespace support to enable in-place metadata updates and cross-namespace contention studies, while maintaining shared physical media under a realistic timing model. Key contributions include a detailed internal design of write/read/erase paths under constrained resources, file-system metadata support, per-chip command queues, flexible block management, and non-power-of-two zone size compatibility, plus extensive case studies on F2FS behavior, data migration strategies, and L2P cache strategies. The results demonstrate that ConZone+ can accurately reflect consumer-device zoned storage behavior, reveal FS and GC-induced bottlenecks, and guide future hardware and software optimizations for improved endurance, performance, and usability in consumer devices. The work provides a practical, open platform for firmware-level exploration and optimization of zoned storage from host file systems to device internals, with tangible implications for ZNS-era consumer storage design and optimization.

Abstract

To facilitate the understanding and efficient enhancement of software and hardware design for consumer-grade zoned flash storage, ConZone is proposed as the first emulator designed to model the resource constraints and architectural features typical of such systems. It incorporates essential components commonly deployed in consumer-grade devices, including limited logical to physical mapping caches, constrained write buffers, and hybrid flash media management. However, ConZone cannot be mounted with the file system due to the lack of in-place update capability, which is required by the metadata area of F2FS. To improve the usability of the emulator, ConZone+ extends ConZone with support for a block interface. We also provide a script to help the deployment and introduces several enhancements over the original version. Users can explore the internal architecture of consumer-grade zoned flash storage and integrate their optimizations with system software using ConZone+. We validate the accuracy of ConZone+ by comparing a hardware architecture representative of consumer-grade zoned flash storage and comparing it with the state-of-the-art. In addition, we conduct several case studies using ConZone+ to investigate the design of zoned storage and explore the inadequacies of the current file system.

Figures (13)

• Figure 1: Comparison of legacy flash storage and zoned flash storage.
• Figure 2: Comparison of current emulators.
• Figure 3: Internals of ConZone.
• Figure 4: Write Path of ConZone
• Figure 5: Read Path of ConZone