Files corrupt on copy

Tony Nelson tonynelson at georgeanelson.com
Sat Jun 27 16:42:10 UTC 2009


On 09-06-27 08:21:22, Andy Campbell wrote:
> I'm having an issue where when I copy files, they are not copying
> correctly - they are corrupt, I've checked using cmp, and generating
> md5sum There are no errors I can see from cp, rsync.
> 
> Initially I though it was a problem with an external USB drives now
> after some testing it seem to be normal SATA drives as well.  I've 
> got a few drives in the box and they all have the same issue.
> 
> I  thought it might be memory - but memtest runs fine, and I
> tried taking out a couple of the sticks - I have 4x2Gb no difference.
> 
> I've written a little rsync script to copy some files around, rsync
> once, then rsync again, using checksum - in theory the second run
> should have nothing to do, but will randomly have to re-copy files.
> 
> Strangely I tried booting off of a live distro ( System Rescue 
> 32bit ) and didn't get any errors.
> 
> The system seem to run fine generally - but I started noticing some 
> of the big files I was syncing to external drives where erroring.  
> Just repeatedly running md5sum on a file gives consistent results - I 
> would have though if was a memory problem that would have give 
> different results.
> 
> I've turned AHCI on in BIOS recently as I've install a WD Raptor,
> and re-installed F10 - would that affect filesystems on other
> drives - is AHCI buggy ?
> 
> I'm using Fedora 10 64bit,  Asus P5Q-E Motherboard,
> Q9950 ( stock speed ), 8Gb Corsair memory
> 
> Any guesses, Kernel bug ? Hardware ? Hopefully not hardware as its
> a fairly recent build.
 ...

I have an old ASUS MB that exhibited similar symptoms (1 bit error, 
same bit, about every 10 GiB copied to disk) from a likely different 
cause:  the FSB and CPU clocks didn't have a simple harmonic 
relationship.  I fixed the problem by setting a higher FSB speed.  I 
think that that ASUS chipset has some problem with a FIFO.  It's 
possible that ASUS still has problems with FIFOs, so you might look at 
the various BIOS bus speed settings.

I hope you don't spend years tracking it down, though you're already 
ahead of me by noticing and documenting the problem.

-- 
____________________________________________________________________
TonyN.:'                       <mailto:tonynelson at georgeanelson.com>
      '                              <http://www.georgeanelson.com/>




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