A Fast, Lightweight, and Reliable File System for Wireless Sensor Networks

Sensor nodes are increasingly used in critical applications. A file storage system that is fast, lightweight, and reliable across device failures is important to safeguard the data that these devices record. A fast and lightweight file system should enable sensed data to be sampled and stored quickly for later transmission, while imposing a small resource footprint. A reliable file system should provide storage integrity in the face of hardware, software, and other failures. We present the design and implementation of LoggerFS, a fast, lightweight, and reliable file system for wireless sensor networks which uses a hybrid memory design consisting of RAM, FRAM, and flash. LoggerFS is engineered to provide fast data storage, have a small memory footprint, and provide data reliability across system failures. Additionally, LoggerFS is designed to be power efficient. LoggerFS adapts a log-structured file system approach, augmented with data persistence and reliability guarantees. A caching mechanism allows for flash wear-leveling and fast data buffering. We present a performance evaluation of LoggerFS using a prototypical in situ sensing platform, and demonstrate between 50% and 800% improvements for various workloads using the FRAM write-back cache.