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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