DFS: A file system for virtualized flash storage

William K. Josephson, Lars A. Bongo, Kai Li, David Flynn

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


This paper presents the design, implementation and evaluation of Direct File System (DFS) for virtualized flash storage. Instead of using traditional layers of abstraction, our layers of abstraction are designed for directly accessing flash memory devices. DFS has two main novel features. First, it lays out its files directly in a very large virtual storage address space provided by FusionIO's virtual flash storage layer. Second, it leverages the virtual flash storage layer to perform block allocations and atomic updates. As a result, DFS performs better and it is much simpler than a traditional Unix file system with similar functionalities. Our microbenchmark results show that DFS can deliver 94,000 I/O operations per second (IOPS) for direct reads and 71,000 IOPS for direct writes with the virtualized flash storage layer on FusionIO's ioDrive. For direct access performance, DFS is consistently better than ext3 on the same platform, sometimes by 20%. For buffered access performance, DFS is also consistently better than ext3, and sometimes by over 149%. Our application benchmarks show that DFS outperforms ext3 by 7% to 250% while requiring less CPU power.

Original languageEnglish (US)
Title of host publicationProceedings of FAST 2010
Subtitle of host publication8th USENIX Conference on File and Storage Technologies
PublisherUSENIX Association
Number of pages15
ISBN (Electronic)9781931971744
StatePublished - Jan 1 2019
Event8th USENIX Conference on File and Storage Technologies, FAST 2010 - San Jose, United States
Duration: Feb 23 2010Feb 26 2010

Publication series

NameProceedings of FAST 2010: 8th USENIX Conference on File and Storage Technologies


Conference8th USENIX Conference on File and Storage Technologies, FAST 2010
Country/TerritoryUnited States
CitySan Jose

All Science Journal Classification (ASJC) codes

  • Hardware and Architecture
  • Software
  • Computer Networks and Communications


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