fsck strangeness

Christopher Key cjk32 at cam.ac.uk
Sat Aug 18 13:04:06 PDT 2007


Bill Moran wrote:
> Christopher Key <cjk32 at cam.ac.uk> 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.
>>     
>
> Don't run fsck on mounted filesystems unless they're mounted read-only.
>
> Although, it's possible I misunderstood your description of the problem.
>
>   
Thanks Eric, Bill,

I must have misunderstood, I was under the impression that running fsck 
on a device with a mounted file system would scan, but not actaully 
write anything, hence its reporting 'NO WRITE'.  I'll reread the fsck 
manpage.

Is running fsck -B /dev/ad8s1e safe, as I understand it, this creates a 
snapshot of the filesystem and scans that.

Regards,

Chris



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