Automatic fsck

Matt Zimmerman mdz at
Wed Aug 13 08:54:20 UTC 2008

On Wed, Aug 13, 2008 at 07:41:18AM +0800, Onno Benschop wrote:
> >> On Mon, Aug 11, 2008 at 11:52:25AM +0100, Matt Zimmerman wrote:
> >>     
> >>> == Filesystem checking / AutoFsck ==
> >>>
> >>> A suggestion was made to the technical board that Ubuntu could be smarter
> >>> about how and when it performs filesystem integrity checks (fsck).
> >>>
> >>> Decision: This should be discussed more widely in the developer community
> >>> Action: Scott to start a thread on ubuntu-devel/-discuss
> >>>       
> One thing that I have not seen in this discussion is the notion that
> fsck might be modified to run incrementally.

That's an interesting idea, though I don't know enough about ext3 to comment
on its feasibility.  Perhaps something to discuss with upstream?

> Another that I did not see is the idea that fsck can be run using -n
> (though ReiserFS and minix aren't supported at the moment). If fsck is
> run in the background and a notification is sent to the
> user/administrator if corruption is found, then active intervention can
> be recommended.

It's easy to prevent fsck from changing the filesystem, but the trouble is
that fsck can't be (usefully) run on a filesystem which is in use (mounted).

> I see with some alarm discussion about reducing the frequency of running
> fsck. I'm running an ext3 laptop and I'm seeing quite regular
> corruptions that require an fsck run to fix. (It may be related to a
> particular kernel, but I've not yet got to the bottom of that.)

That is a very disconcerting (and atypical) problem.  The appearance of
errors in fsck indicates a serious problem which should be investigated, not
a normal condition of wear and tear.

> Fundamentally, in my opinion, fsck is a housekeeping process that is
> required on a regular basis to ensure the sane state of a file-system,
> no matter which one you use, errors do happen, even if there are no bugs
> (ha!), we're talking about tiny magnetic fields affecting the
> information on a hard-drive - this problem is only going to get bigger
> with increased storage density.

I don't think there's any disagreement on this point.  The issues are:

1) The frequency at which fsck runs is somewhat arbitrary for many users,
depending on their usage pattern, and doesn't relate particularly well to
their risk of encountering errors.

2) The fsck runs themselves are very disruptive, blocking access to the
computer when the user wants it.

 - mdz

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