--- On Thu, 28/1/10, Goswin von Brederlow <goswin-v-b@web.de> wrote:

  

quoted

From: Goswin von Brederlow <redacted>
Subject: Re: Why does one get mismatches?
To: linux-raid@vger.kernel.org
Date: Thursday, 28 January, 2010, 20:24
"Tirumala Reddy Marri" [off-list ref]
writes:

    

quoted

I just tried and miss-match count is zero.
      

Interesting, is XOR engine
    

quoted

doing something wrong ? . Then I ran a test where I
      

raw-write the file
    

quoted

to /dev/md0. Then did the raw-read for the same size.
      

In this case XOR
    

quoted

matched as expected. Then I failed a drive using
      

"mdadm -f /dev/md0
    

quoted

/dev/sda". Then I read the same size data again from
      

/dev/md0. And
    

quoted

checksum matches too. 
What is this mean XOR engine is doing right thing. But
      

"chec/repair"
    

quoted

test is not functioning properly with XOR-engine ?

Or is this something to do with  how the buffers
      

are handled ? may they
    

quoted

are cached ?


-Marri
      

No idea. But if everything works without the XOR engine and
gives
mismatches with then I would think there is a software or
hardware error
there and not in the cable or disks.

MfG
        Goswin
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i think my RAM is fecked - does that sound like a possible cause? memtest86 gives PAGES of red errors when run but the POST gives nothing and the machine boots.... it has 512MB

i have some more on order as a speculative..