Loeck, YannickYannickLoeckDietrich, ChristianChristianDietrichKulau, UlfUlfKulau2026-06-172026-06-172026-05International Conference on Embedded Artificial Intelligence and Sensing Systems, SenSys 2026https://hdl.handle.net/11420/63526NOR flash memory is widely used as storage in embedded systems as it offers dense non-volatile memory up to the gigabit range while being more reliable than NAND flash. To avoid the cost of a standalone flash controller in such small systems, specialized flash file systems are used to handle the limited write endurance and asymmetric program/erase characteristics. While many NOR file systems exist and are extensively deployed, there is a lack of systematic comparisons of their performance. In this paper, we present vflashsim, a simulator for capturing interactions between file systems and flash memory and for running representative benchmarks. Unlike evaluations on physical hardware, our simulation-based approach avoids prohibitively long erase latencies and cell wear. We implement a NOR flash model and, using vflashsim, evaluate four representative file systems, SPIFFS, LittleFS, YAFFS2, and NF2FS, in terms of write amplification, garbage-collection behavior, and RAM utilization. Our analysis shows how design choices and implementation bugs, such as excessive device scanning, unconditional sector erases, and a lack of garbage collection in allocation paths, cause substantial performance issues. Additionally, we identify how to provoke failure conditions in different file systems, which can result in unrecoverable crashes. Among the evaluated file systems, YAFFS demonstrates the best overall performance and reliability at the cost of high RAM usage, whereas a modified LittleFS remains the best option for more memory-constrained systems. Since performance trade-offs vary by workload and hardware constraints, no single file system is universally optimal. With vflashsim, we provide a tool that enables developers and users of flash file systems to analyze their behavior under diverse configurations and workloads.enhttps://creativecommons.org/licenses/by/4.0/flash file systemNOR flashsimulationComputer Science, Information and General Works::003: Systems Theory::003.5: Communication and ControlComputer Science, Information and General Works::006: Special computer methods::006.3: Artificial IntelligenceConference Paper10.1145/3774906.380279310.15480/882.17325