I think your notion that you have an HP CCISS driver in this older
kernel that just doesn't drive your card very fast is worth exploring.
What I sometimes do in the situation you're in is boot a Linux
distribution that comes with a decent live CD, such as Debian or
Ubuntu. Just mount the suspect drive, punch up read-ahead, and re-test
performance. That should work well enough to do a simple dd test, and
probably well enough to compile and run bonnie++ too. If that gives
good performance numbers, it should narrow the list of possible causes
considerably. You really need to separate out "bad driver" from the
other possibilities here given what you've described, and that's a low
impact way to do it.
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Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us