Re: Data corruption

[Jeffrey V. Merkey]

paul wrote:

If you remove memory and it goes away it probably is related to ECC 
issues.  Replace the upper 2GB of memory -- it appears to
have a defect.  If it persists after replacing the memory, then it may 
be software related.   Doesn't sound like it though.  Sounds like the
same problem I have seen.    

Jeff

> Hi, thank you for your answer, actually I removed 2Gb of physical memory and 
> the problem gone away .. but my system needs 4Gb.
>
> I reproduce it under Xen and without xen (on a standard kernel) I can't tell 
> you how mutch difference I have betwwen files, regarding a 4 month system 
> running on these condition, I think the number of errors are rare but 
> existing, during my tests with 100M files I did not get a lot of error, so we 
> can assume 2 or 3 bytes in error in 300M files... (expectation)
>
> I try to avaoid it by disabeling memory relocation on my MB ... in that case 
> the system only detect 2.8G (and Linux too), The probem still there.
>
> It seems to be based on an Asus P5B-VM problem as this one have a lot of with 
> 4Gb... But it should be certified on Windows up to 8Gb... (but I did not have 
> that strange OS to check). So a workaround should exists.
>
>
> Le mercredi 8 août 2007 01:57, vous avez écrit :
>  
>
> > paul wrote:
> >    
> >
> > > Since 2-3 month I have some random data corruption on my Linux server,
> > > after checking disks independently (i'm using raid1on 2 sata disk, the
> > > problem is the same w/o raid) and memory, hardware simce to be out of
> > > cause...
> > >
> > > Here is my problem:
> > > => head --bytes=300m  /dev/urandom > test
> > > => for i in `seq 0 9` ; do cp test test$i ; done
> > > => md5sum test*
> > > I got :
> > > 014666c728c9e3b8299579fae499864a  test
> > > 014666c728c9e3b8299579fae499864a  test0
> > > 333fd93d093ac612cd8d5f65628f734e  test1
> > > 1ab6ee68c6a7d9ff5a05f9d63f0f6df6  test2
> > > 96e96483e3175a59c9c05b6720514e1e  test3
> > > 014666c728c9e3b8299579fae499864a  test4
> > > b24dbccc9f4831f8825ab4a55a3be4aa  test5
> > > 8493efc9c14e4b5c162ac23696fbc16a  test6
> > > 6a5f4301f66d0379049d79d0e14e2a87  test7
> > > 2c81cfa1c3a03aba134574922ee5d75c  test8
> > > 2ea15c8392bfd0123472a80125bb3abe  test9
> > >
> > > ^^^ that sounds really bad for my data :(
> > >      
> > It does indeed.  Can you try comparing the data to see precisely how much
> > differs between the versions?  md5sums don't distinguish between a
> > single-bit error and a block or page-sized error, but the distinction is
> > critical in determining what broke.
> >
> > Can you reproduce this on a recent upstream baremetal (non-Xen) kernel?  If
> > so, does it go away when you boot with mem=3000M?
> >
> > 	-- Chris
> >    
>
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