fsck strangeness

[Erik Trulsson]

On Sat, Aug 18, 2007 at 08:21:42PM +0100, Christopher Key wrote:
> Hello,
> 
> I'm having some rather strange behaviour with fsck.
> 
> When I boot the system, it asserts that all the file systems are clean, but 
> subsequently running an fsck on /dev/ad8s1e (mounted as /var) detects 
> errors.  Even if this first check is run whilst the file system is mounted, 
> and is hence run in NO WRITE mode, a second check doesn't find block 
> errors.  If I then unmount the file system and check the disk, it's fine, 
> as indeed it is if I unmount, remount, then check.  However, if I then 
> reboot, the process repeats, and an fsck immediately after reboot will find 
> errors again.  If I bring the system up in single user mode, and run fsck 
> either before or after mounting /var, it finds no errors.
> 
> I'm running 6.2_RELEASE with a custom kernel based upon generic-smp, but 
> with a lot of unecessary bits removed, and geom_mirror compiled in.  I 
> don't think it's the drive that's at fault, all the other partitions in the 
> slice are fine, it's a fairly new drive, and it passes a self test quite 
> happily.  Included below is a transcript that attempt to show what's going 
> on in detail, is there anything else relevant?
> 
> Can anyone suggest what might be going on and how to fix it, or suggest 
> some slightly better diagnostics?  Apologies if this is an RTFM issue, I 
> have had a good dig through the handbook, but can't seem to find anything 
> that helps.
> 

Running fsck on a file system that has been mounted read/write will almost
always report spurious errors and can really screw up the disk if it tries
to 'correct' those errors.

You should normally not run fsck on a mounted filesystem and you should
*NEVER* run fsck on a filesystem that has been mounted read/write.




-- 
<Insert your favourite quote here.>
Erik Trulsson
ertr1013 at student.uu.se