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.

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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