SNFS: Small Writes Optimization for Log-Structured File System Based-on Non-Volatile Main Memory

Emerging non-volatile main memories (NVMMs) technologies can provide both data persistence and high performance at memory level. The design of existing file systems for NVMM has to handle the data durability problem between CPU cache and NVMM. However, most NVMM-aware file systems could not meet the strong data consistency requirement of applications with data structures, e.g. B-Tree. Traditional techniques, such as copy-on-write and journaling, delivering data consistency, have defects of write amplification and data copy, respectively. In this paper, we explore SNFS, one log-structured file system with optimization of data consistency based-on non-volatile main memory, providing high performance for applications with small writes. Specifically, SNFS adopts a small data-log mechanism to journal fine-grained data writes. It also uses in-place writes to minimize memory footprint for small data updating and accelerates data block locating with hashing strategy. Finally, we evaluate SNFS's performance with several write-intensive workloads, and experimental results show that SNFS improves the system throughput by up to 23 times compared to state-of-the-art file systems and reduces the execution time by up to 65.5%.