On Thu, 4 Oct 2007, Andrew Clayton wrote:

On Thu, 4 Oct 2007 10:10:02 -0400 (EDT), Justin Piszcz wrote:

quoted

Also, did performance just go to crap one day or was it gradual?

IIRC I just noticed one day that firefox and vim was stalling. That was
back in February/March I think. At the time the server was running a
2.6.18 kernel, since then I've tried a few kernels in between that and
currently 2.6.23-rc9

Something seems to be periodically causing a lot of activity that
max's out the stripe_cache for a few seconds (when I was trying
to look with blktrace, it seemed pdflush was doing a lot of activity
during this time).

What I had noticed just recently was when I was the only one doing IO
on the server (no NFS running and I was logged in at the console) even
just patching the kernel was crawling to a halt.

quoted

Justin.

Cheers,

Andrew
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Besides the NCQ issue your problem is a bit perpelxing..

Just out of curiosity have you run memtest86 for at least one pass to make 
sure there were no problems with the memory?

Do you have a script showing all of the parameters that you use to 
optimize the array?

Also mdadm -D /dev/md0 output please?

What distribution are you running? (not that it should matter, but just 
curious)

Justin.