hFS: a hybrid file system prototype for improving small file and metadata performance

ABSTRACT

Two oft-cited file systems, the Fast File System (FFS) and the Log-Structured File System (LFS), adopt two sharply different update strategies---update-in-place and update-out-of-place. This paper introduces the design and implementation of a hybrid file system called hFS, which combines the strengths of FFS and LFS while avoiding their weaknesses. This is accomplished by distributing file system data into two partitions based on their size and type. In hFS, data blocks of large regular files are stored in a data partition arranged in a FFS-like fashion, while metadata and small files are stored in a separate log partition organized in the spirit of LFS but without incurring any cleaning overhead. This segregation makes it possible to use more appropriate layouts for different data than would otherwise be possible. In particular, hFS has the ability to perform clustered I/O on all kinds of data---including small files, metadata, and large files. We have implemented a prototype of hFS on FreeBSD and have compared its performance against three file systems, including FFS with Soft Updates, a port of NetBSD's LFS, and our lightweight journaling file system called yFS. Results on a number of benchmarks show that hFS has excellent small file and metadata performance. For example, hFS beats FFS with Soft Updates in the range from 53% to 63% in the PostMark benchmark.

REFERENCES

• 1: Marshall K. McKusick , William N. Joy , Samuel J. Leffler , Robert S. Fabry, A fast file system for UNIX, ACM Transactions on Computer Systems (TOCS), v.2 n.3, p.181-197, Aug. 1984 [doi>10.1145/989.990]
• 2: The IBM JFS project. http://oss.software.ibm.com/developerworks/opensource/jfs/.
• 3: The SGI XFS project. http://oss.sgi.com/projects/xfs/.
• 4: The ReiserFS project, http://www.namesys.com/.
• 5: Stephen C. Tweedie. Journaling the Linux ext2fs Filesystem. LinuxExpo'98, May 1998.
• 6: Mendel Rosenblum , John K. Ousterhout, The design and implementation of a log-structured file system, ACM Transactions on Computer Systems (TOCS), v.10 n.1, p.26-52, Feb. 1992 [doi>10.1145/146941.146943]
• 7: Margo Seltzer , Keith Bostic , Marshall Kirk Mckusick , Carl Staelin, An implementation of a log-structured file system for UNIX, Proceedings of the USENIX Winter 1993 Conference Proceedings on USENIX Winter 1993 Conference Proceedings, p.3-3, January 25-29, 1993, San Diego, California
• 8: Dave Hitz, James Lau and Michael Malcolm. File System Design for a NFS File Server Appliance. Tech. Report TR 3002, Network Appliance Inc, updated 2005.
• 9: Keith Muller , Joseph Pasquale, A high performance multi-structured file system design, Proceedings of the thirteenth ACM symposium on Operating systems principles, p.56-67, October 13-16, 1991, Pacific Grove, California, United States
• 10: Keith A. Smith , Margo Seltzer, A comparison of FFS disk allocation policies, Proceedings of the Annual Technical Conference on USENIX 1996 Annual Technical Conference, p.2-2, January 22-26, 1996, San Diego, CA
• 11: Steve Pate , Fred Van Den Bosch, UNIX Filesystems: Evolution, Design and Impemenation, John Wiley & Sons, Inc., New York, NY, 2003
• 12: Gregory R. Ganger , M. Frans Kaashoek, Embedded inodes and explicit grouping: exploiting disk bandwidth for small files, Proceedings of the Annual Technical Conference on Proceedings of the USENIX 1997 Annual Technical Conference, p.1-1, January 06-10, 1997, Anaheim, California
• 13: Gregory R. Ganger , Yale N. Patt, Metadata update performance in file systems, Proceedings of the 1st USENIX conference on Operating Systems Design and Implementation, p.5-es, November 14-17, 1994, Monterey, California
• 14: Marshall Kirk McKusick , Gregory R. Ganger, Soft updates: a technique for eliminating most synchronous writes in the fast filesystem, Proceedings of the Annual Technical Conference on 1999 USENIX Annual Technical Conference, p.24-24, June 06-11, 1999, Monterey, California
• 15: Margo I. Seltzer , Gregory R. Ganger , M. Kirk McKusick , Keith A. Smith , Craig A. N. Soules , Christopher A. Stein, Journaling versus soft updates: asynchronous meta-data protection in file systems, Proceedings of the Annual Technical Conference on 2000 USENIX Annual Technical Conference, p.6-6, June 18-23, 2000, San Diego, California
• 16: Jun Wang , Yiming Hu, WOLF - A Novel Reordering Write Buffer to Boost the Performance of Log-Structured File Systems, Proceedings of the Conference on File and Storage Technologies, p.47-60, January 28-30, 2002
• 17: Trevor Blackwell , Jeffrey Harris , Margo Seltzer, Heuristic cleaning algorithms in log-structured file systems, Proceedings of the USENIX 1995 Technical Conference Proceedings on USENIX 1995 Technical Conference Proceedings, p.23-23, January 16-20, 1995, New Orleans, Louisiana
• 18: Jeanna Neefe Matthews , Drew Roselli , Adam M. Costello , Randolph Y. Wang , Thomas E. Anderson, Improving the performance of log-structured file systems with adaptive methods, Proceedings of the sixteenth ACM symposium on Operating systems principles, p.238-251, October 05-08, 1997, Saint Malo, France
• 19: Drew Roselli , Jacob R. Lorch , Thomas E. Anderson, A comparison of file system workloads, Proceedings of the Annual Technical Conference on 2000 USENIX Annual Technical Conference, p.4-4, June 18-23, 2000, San Diego, California
• 20: Ian Dowse , David Malone, Recent Filesystem Optimisations on FreeBSD, Proceedings of the FREENIX Track: 2002 USENIX Annual Technical Conference, p.245-258, June 10-15, 2002
• 21: Sape J. Mullender , Andrew S. Tanenbaum, Immediate files, Software—Practice & Experience, v.14 n.4, p.365-368, April 1984 [doi>10.1002/spe.4380140407]
• 22: The FreeBSD Project. http://www.freebsd.org.
• 23: The NetBSD Project. http://www.netbsd.org.
• 24: Zhihui Zhang , Kanad Ghose, yFS: A Journaling File System Design for Handling Large Data Sets with Reduced Seeking, Proceedings of the 2nd USENIX Conference on File and Storage Technologies, March 31-31, 2003, San Francisco, CA
• 25: Keith A. Smith , Margo I. Seltzer, File system aging—increasing the relevance of file system benchmarks, Proceedings of the 1997 ACM SIGMETRICS international conference on Measurement and modeling of computer systems, p.203-213, June 15-18, 1997, Seattle, Washington, United States
• 26: Jeffrey Katcher. PostMark: A New File System Benchmark. Technical Report TR3022. Network Appliance Inc., October 1997.
• 27: Paul Barford , Mark Crovella, Generating representative Web workloads for network and server performance evaluation, Proceedings of the 1998 ACM SIGMETRICS joint international conference on Measurement and modeling of computer systems, p.151-160, June 22-26, 1998, Madison, Wisconsin, United States
• 28: Juan Piernas , Toni Cortes , José M. García, DualFS: a new journaling file system without meta-data duplication, Proceedings of the 16th international conference on Supercomputing, June 22-26, 2002, New York, New York, USA [doi>10.1145/514191.514213]
• 29: Marshall K. McKusick, Running "fsck" in the Background, Proceedings of the BSDCon 2002, p.55-64, February 11-14, 2002
• 30: Michael Stonebraker, Operating system support for database management, Communications of the ACM, v.24 n.7, p.412-418, July 1981 [doi>10.1145/358699.358703]
• 31: Wenguang Wang , Yanping Zhao , Rick Bunt, HyLog: A High Performance Approach to Managing Disk Layout, Proceedings of the 3rd USENIX Conference on File and Storage Technologies, March 31-31, 2004, San Francisco, CA

INDEX TERMS

Primary Classification:
  D. Software
  D.4 OPERATING SYSTEMS
      D.4.2 Storage Management
          Subjects: Allocation/deallocation strategies

Additional Classification:
  D. Software
  D.4 OPERATING SYSTEMS
      D.4.3 File Systems Management

General Terms:
Algorithms, Design, Performance

Keywords:
disk inodes, file systems, metadata journaling, update strageties