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


"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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