UNEXPECTED SOFT UPDATE INCONSISTENCY; RUN fsck MANUALLY

[Jeremy Chadwick]

On Fri, Sep 26, 2008 at 09:33:41PM -0700, Derek Kuli??ski wrote:
> Hello Jeremy,
> 
> Sunday, September 21, 2008, 3:07:20 PM, you wrote:
> 
> > Consider using background_fsck="no" in /etc/rc.conf if you prefer the
> > old behaviour.  Otherwise, boot single-user then do the fsck.
> 
> Actually what's the advantage of having fsck run in background if it
> isn't capable of fixing things?
> Isn't it more dangerous to be it like that? i.e. administrator might
> not notice the problem; also filesystem could break even further...

This question should really be directed at a set of different folks,
e.g. actual developers of said stuff (UFS2 and soft updates in
specific), because it's opening up a can of worms.

I believe it has to do with the fact that there is much faith given to
UFS2 soft updates -- the ability to background fsck allows the user to
boot their system and have it up and working (able to log in, etc.) in a
much shorter amount of time[1].  It makes the assumption that "everything
will work just fine", which is faulty.

It also gives the impression of a journalled filesystem, which UFS2 soft
updates are not.  gjournal(8) on the other hand, is, and doesn't require
fsck at all[2].

I also think this further adds fuel to the "so why are we enabling soft
updates by default and using UFS2 as a filesystem again?" fire.  I'm
sure someone will respond to this with "So use ZFS and shut up".  *sigh*

[1]: http://lists.freebsd.org/pipermail/freebsd-questions/2004-December/069114.html
[2]: http://lists.freebsd.org/pipermail/freebsd-questions/2008-April/173501.html

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |