HMVFS: A Hybrid Memory Versioning File System

Abstract: The byte-addressable Non-Volatile Memory (NVM) offers fast, fine-grained access to persistent storage, and a large volume of recent researches are conducted on developing NVM-based in-memory file systems. However, existing approaches focus on low-overhead access to the memory and only guarantee the consistency between data and metadata. In this paper, we address the problem of maintaining consistency among continuous snapshots for NVM-based in-memory file systems. We propose a Hybrid Memory Versioning File System (HMVFS) that achieves fault tolerance efficiently and has low impact on I/O performance. Our results show that HMVFS provides better performance on snapshotting compared with the traditional versioning file systems for many workloads. Specifically, HMVFS has lower snapshotting overhead than BTRFS and NILFS2, improving by a factor of 9.7 and 6.6, respectively. Furthermore, HMVFS imposes minor performance overhead compared with the state-of-the-art in-memory file systems like PMFS.