Question about forcing fsck at boottime

Chris Rees utisoft at
Tue Mar 31 04:03:12 PDT 2009

2009/3/31 manish jain <invalid.pointer at>:

> BTW, a lot of people who posted replies thought I was not aware that a preen
> is always executed at startup. When I said I wanted to force an fsck, I
> meant 'fsck -fy'. As for background checks, they are - in my opinion - a
> real nightmare. Even though I am just a learner on FreeBSD still, I can
> assure anyone, putting background_fsck="NO" into your rc.conf is one of the
> best things you can do.
> As for the reason why I want to force fsck is that it has now happened 3
> timed that, after a clean and proper shutdown - with no foreign filesystems
> mounted, FreeBSD has complained on system restart (twice on a 5.x
> distribution I had briefly used and now once on 7.1) that / was not properly
> unmounted. Having bgfsck enabled is like inviting a dragon to dinner when
> this happens.

Sorry, but I have to disagree. The filesystem that FreeBSD uses (UFS
to some, FFS to others) has a feature known as 'snapshots', something
alien to people in the Linux world. What this means, is that one can
take a 'snapshot' of a drive's state (somewhat like a versioning tag),
and mount, dump, OR fsck it. The point of a background fsck is that
the SNAPSHOT is fsck'd, and only if there is a problem (which there
usually isn't, due to soft-updates meaning that data are rarely lost
on power loss) does fsck require write access to the volume in

This is also why you can dump a live filesystem in FreeBSD.

Just to reiterate something said a thousand times, there is NOTHING
WRONG with background fscks, and just because something doesn't work
well for GNU/Linux doesn't mean it doesn't work with FreeBSD. There
are many differences, after all.


A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
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