FlatFS: Flatten Hierarchical File System Namespace on Non-volatile Memories

Authors: 

Miao Cai, Key Laboratory of Water Big Data Technology of Ministry of Water Resources, Hohai University; School of Computer and Information, Hohai University; State Key Laboratory for Novel Software Technology, Nanjing University; Junru Shen, School of Computer and Information, Hohai University; Bin Tang, Key Laboratory of Water Big Data Technology of Ministry of Water Resources, Hohai University; Hao Huang, State Key Laboratory for Novel Software Technology, Nanjing University; Baoliu Ye, State Key Laboratory for Novel Software Technology, Nanjing University; Key Laboratory of Water Big Data Technology of Ministry of Water Resources, Hohai University; School of Computer and Information, Hohai University

Abstract: 

The conventional file system provides a hierarchical namespace by structuring it as a directory tree. Tree-based namespace structure leads to inefficient file path walk and expensive namespace tree traversal, underutilizing ultra-low access latency and good sequential performance provided by non-volatile memory systems. This paper proposes FlatFS, a NVM file system that features a flat namespace architecture while provides a compatible hierarchical namespace view. FlatFS incorporates three novel techniques: coordinated file path walk model, range-optimized NVM-friendly B^{r} tree, and write-optimized compressed index key layout, to fully exploit flat namespace structure to improve file system namespace performance on high-performance NVMs. Evaluation results demonstrate that FlatFS achieves significant performance improvements for metadata-intensive benchmarks and real-world applications compared to other file systems.

Open Access Media

USENIX is committed to Open Access to the research presented at our events. Papers and proceedings are freely available to everyone once the event begins. Any video, audio, and/or slides that are posted after the event are also free and open to everyone. Support USENIX and our commitment to Open Access.

BibTeX
@inproceedings {280722,
author = {Miao Cai and Junru Shen and Bin Tang and Hao Huang and Baoliu Ye},
title = {{FlatFS}: Flatten Hierarchical File System Namespace on Non-volatile Memories},
booktitle = {2022 USENIX Annual Technical Conference (USENIX ATC 22)},
year = {2022},
isbn = {978-1-939133-29-30},
address = {Carlsbad, CA},
pages = {899--914},
url = {https://www.usenix.org/conference/atc22/presentation/cai},
publisher = {USENIX Association},
month = jul,
}

Presentation Video