On Tue, Jan 29, 2013 at 07:43:09PM +0100, Wolfgang Denk wrote:
[...]

I am not a friend of quick conclusions in cases like this, but I think
that hardware issues are very unlikely to hit with identical effects
simultaneously on 3 different machines in 2 different locations.

Hi Wolfgang,

yep, I think the same.
If all error report by raid6check, on the three
systems, are "unknown", then it seems to be a
software problem.

quoted

quoted

OK, add more hardware details...

A: Supermicro X8SAX mainboard, Core i7 CPU 950 @ 3.07GHz, 24 GB RAM
H: Supermicro X8ST3 mainboard, Xeon CPU W3565  @ 3.20GHz, 24 GB RAM
X: Supermicro X8SAX mainboard, Core i7 CPU 950 @ 3.07GHz, 24 GB RAM

 
What does the kernel log says about the choosen
RAID6 algorithm?

System A:

[   57.121902] raid6: sse2x1    7660 MB/s
[   57.138892] raid6: sse2x2    8687 MB/s
[   57.155890] raid6: sse2x4    9789 MB/s
[   57.155891] raid6: using algorithm sse2x4 (9789 MB/s)
[   57.155892] raid6: using ssse3x2 recovery algorithm

System H:

[   45.360607] raid6: sse2x1    7753 MB/s
[   45.403614] raid6: sse2x2    8777 MB/s
[   45.445612] raid6: sse2x4    9773 MB/s
[   45.472547] raid6: using algorithm sse2x4 (9773 MB/s)
[   45.503347] raid6: using ssse3x2 recovery algorithm

System X:

[   51.471793] raid6: sse2x1    3996 MB/s
[   51.517657] raid6: sse2x2    4851 MB/s
[   51.566579] raid6: sse2x4    4960 MB/s
[   51.598831] raid6: using algorithm sse2x4 (4960 MB/s)
[   51.638697] raid6: using ssse3x2 recovery algorithm

This ssse3x3 I do not know, it seems new to me,
but I might be wrong, we would need someone
with more insight of RAID6 implementation.
 

Note: I remembered that I converted yet another machine which has a
(smaller) RAID6 array (4 x SAMSUNG SpinPoint F1 HE502IJ) on a less
powerful PC (Gigabyte P35-DS3R mainboard, Intel Core 2 Duo CPU E6750
@ 2.66GHz, 8 GB RAM).  This shows NO problems (so far).  Here I have:

[   11.253015] raid6: sse2x1    1902 MB/s
[   11.270021] raid6: sse2x2    2296 MB/s
[   11.287274] raid6: sse2x4    3171 MB/s
[   11.287533] raid6: using algorithm sse2x4 (3171 MB/s)
[   11.288127] raid6: using ssse3x2 recovery algorithm


If you can draw any conclusions from that - I can't.

It is also the slower...
Nevertheless, at this point, I cannot draw
any conclusions too... Sorry.
 
bye,

-- 

piergiorgio