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    SubjectRe: soft update vs journaling?
    El Sun, 22 Jan 2006 04:31:44 -0500,
    Theodore Ts'o <tytso@mit.edu> escribió:


    > One major downside with Soft Updates that you haven't mentioned in
    > your note, is that the amount of complexity it adds to the filesystem
    > is tremendous; the filesystem has to keep track of a very complex
    > state machinery, with knowledge of about the ordering constraints of
    > each change to the filesystem and how to "back out" parts of the
    > change when that becomes necessary.


    And FreeBSD is implementing journaling for UFS and getting rid of
    softupdates [1]. While this not proves that softupdates is "a bad idea",
    i think this proves why the added sofupdates complexity doesn't seem
    to pay off in the real world.

    [1]: http://lists.freebsd.org/pipermail/freebsd-hackers/2004-December/009261.html

    "4. Journaled filesystem. While we can debate the merits of speed and
    data integrety of journalling vs. softupdates, the simple fact remains
    that softupdates still requires a fsck run on recovery, and the
    multi-terabyte filesystems that are possible these days make fsck a very
    long and unpleasant experience, even with bg-fsck. There was work at
    some point at RPI to add journaling to UFS, but there hasn't been much
    status on that in a long time. There have also been proposals and
    works-in-progress to port JFS, ReiserFS, and XFS. Some of these efforts
    are still alive, but they need to be seen through to completion"
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