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Soft updates, hard problemsSoft updates, hard problemsPosted Jul 2, 2009 12:07 UTC (Thu) by rsidd (subscriber, #2582)Parent article: Soft updates, hard problems
As someone who used FreeBSD for a long time and have lurked on its mailing lists: softupdates and background fsck (which made their appearance around FreeBSD 5.0) proved notoriously unstable -- particularly the background fsck, which many developers warned against for a long time. Bugs crop up to this day. And, apparently, pretty much the only person who can debug it is Kirk McKusick.
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Soft updates, hard problems Posted Jul 3, 2009 9:41 UTC (Fri) by rsidd (subscriber, #2582) [Link] Replying to myself: FreeBSD itself has moved to journalling (via gjournal) since version 7. I'm not sure what the defaults are on a new install, but (a) the default kernel supports it, and (b) for best performance, disabling softupdates is recommended. So I have to assume that not only is this article spot-on, but FreeBSD itself has had enough of softupdates. People who continue to bring it up on linux lists are probably not the people who are likely to be able to implement it, or appreciate the issues. Thanks for the very readable clarification!
Soft updates, hard problems Posted Jul 12, 2009 8:47 UTC (Sun) by takeda (guest, #59543) [Link]
Emmm... Long time FreeBSD user as well...
Actually the problem with soft updates isn't really in FreeBSD itself, it's in hard drives which reorder writes for speed. That most often happens because of the caching. On top of that many drives lie about writing things to disk while in fact the data is still in cache.
The fix for that is to disable cache on the disk (setting hw.ata.wc=0 on boot), unfortunately that reduces performance.
As for FreeBSD switching to journaling, that's not enteirly true... gjournal is part of GEOM framework and gjournal was one of tools showing what GEOM can do (among with geli, gshsec etc). It also doesn't work exactly the same as other journaling since it works on a block level (GEOM work under the filesystem layer).
If anything, the UFS might be replaced by ZFS.
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