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7.4 Log based file systems




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This article is from the storage FAQ part2, by Rodney D. Van Meter with numerous contributions by others.

7.4 Log based file systems

    Further Information:
    %z InProceedings
    %K hpdb:Rosenblum91
    %s golding@cis.ucsc.edu (Thu Oct 17 11:12:07 1991)
    %A Mendel Rosenblum
    %A John K. Ousterhout
    %y UCBCS.
    %T The design and implementation of a log-structured file system
    %C Proc. 13th SOSP.
    %c Asilomar, Pacific Grove, CA
    %p ACM. SIGOPS
    %D 13 Oct. 1991
    %P 1 15
    %x This paper presents a new technique for disk storage management
    %x called a log-structured file system.  A log-structured file system
    %x writes all modifications to disk sequentially in a log-like
    %x structure, thereby speeding up both file writing and crash
    %x recovery.  The log is the only structure on disk; it contains
    %x indexing information so that files can be read back from the log
    %x efficiently.  In order to maintain large free areas on disk for
    %x fast writing, we divide the log into segments and use a segment
    %x cleaner to compress the live information from heavily fragmented
    %x segments.  We present a series of simulations that demonstrate the
    %x efficiency of a simple cleaning policy based on cost and benefit.
    %x We have implemented a prototype log-structured file system called
    %x Sprite LFS; it outperforms current Unix file systems by an order of
    %x magnitude for small-file writes while matching or exceeding Unix
    %x performance for reads and large writes.  Even when the overhead for
    %x cleaning is included, Sprite LFS can use 70% of the disk bandwidth
    %x for writing, whereas Unix file systems typically can use only
    %x 5--10%.

(tage@cs.utwente.nl)

Also, these papers:

Ousterhout and Douglis, "Beating the I/O Bottleneck: A Case for Log-
structured File Systems", Operating Systems Review, No. 1, Vol. 23, pp.
11-27, 1989, also available as Technical Report UCB/CSD 88/467.

Rosenblum and Ousterhout, "The Design and Implementation of a Log-
Structured File System", ACM SIGOPS Operating Systems Review, No. 5, Vol.
25, 1991.

Seltzer, "File System Performance and Transaction Support", PhD Thesis,
University of California, Berkeley, 1992, also available as Technical
Report UCB/ERL M92.

Seltzer, Bostic, McKusick and Staelin, "An Implementation of a Log-
Structured File System for UNIX", Proc. of the Winter 1993 USENIX Conf.,
pp. 315-331, 1993.

listed from the man page for mount_lfs under FreeBSD-2.1.5. (rdv, 97/1/17)
    

 

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