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Date:      Tue, 31 Mar 2009 12:03:10 +0100
From:      Chris Rees <utisoft@googlemail.com>
To:        FreeBSD Mailing List <freebsd-questions@freebsd.org>,  Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>, invalid.pointer@gmail.com
Subject:   Re: Question about forcing fsck at boottime
Message-ID:  <b79ecaef0903310403l33df4eb2q16223504bdb8ff98@mail.gmail.com>
In-Reply-To: <49D1F0BA.7050209@gmail.com>
References:  <49D1B297.8060307@gmail.com> <20090331080137.31122795@gluon.draftnet> <49D1F0BA.7050209@gmail.com>

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2009/3/31 manish jain <invalid.pointer@gmail.com>:

> 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
question.

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.

Chris

-- 
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