Optimizing every operation in a write-optimized file system

Jun Yuan, Yang Zhan, William Jannen, Prashant Pandey, Amogh Akshintala, Kanchan Chandnani, Pooja Deo, Zardosht Kasheff, Leif Walsh, Michael A. Bender, Martin Farach-Colton, Rob Johnson, Bradley C. Kuszmaul, Donald E. Porter

Research output: Chapter in Book/Report/Conference proceedingConference contribution

34 Scopus citations


File systems that employ write-optimized dictionaries (WODs) can perform random-writes, metadata updates, and recursive directory traversals orders of magnitude faster than conventional file systems. However, previous WOD-based file systems have not obtained all of these performance gains without sacrificing performance on other operations, such as file deletion, file or directory renaming, or sequential writes. Using three techniques, late-binding journaling, zoning, and range deletion, we show that there is no fundamental trade-off in write-optimization. These dramatic improvements can be retained while matching conventional file systems on all other operations. BetrFS 0.2 delivers order-of-magnitude better performance than conventional file systems on directory scans and small random writes and matches the performance of conventional file systems on rename, delete, and sequential I/O. For example, BetrFS 0.2 performs directory scans 2.2× faster, and small random writes over two orders of magnitude faster, than the fastest conventional file system. But unlike BetrFS 0.1, it renames and deletes files commensurate with conventional file systems and performs large sequential I/O at nearly disk bandwidth. The performance benefits of these techniques extend to applications as well. BetrFS 0.2 continues to outperform conventional file systems on many applications, such as as rsync, git-diff, and tar, but improves git-clone performance by 35% over BetrFS 0.1, yielding performance comparable to other file systems.

Original languageEnglish (US)
Title of host publicationProceedings of the 14th USENIX Conference on File and Storage Technologies, FAST 2016
PublisherUSENIX Association
Number of pages14
ISBN (Electronic)9781931971287
StatePublished - Jan 1 2019
Event14th USENIX Conference on File and Storage Technologies, FAST 2016 - Santa Clara, United States
Duration: Feb 22 2016Feb 25 2016

Publication series

NameProceedings of the 14th USENIX Conference on File and Storage Technologies, FAST 2016


Conference14th USENIX Conference on File and Storage Technologies, FAST 2016
Country/TerritoryUnited States
CitySanta Clara

ASJC Scopus subject areas

  • Hardware and Architecture
  • Software
  • Computer Networks and Communications


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