Messages in this thread | | | Date | Sun, 22 Jan 2006 20:00:18 -0500 | From | John Richard Moser <> | Subject | Re: soft update vs journaling? |
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Diego Calleja wrote: > 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. >
Yeah, the huge TB fsck thing became a problem. I wonder still if it'd be useful for small vfat file systems (floppies, usb drives); nobody has led me to believe it's definitely feasible to not corrupt meta-data in this way.
I guess journaling is looking a lot better. :)
> [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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