Qlogic 2200 performance issues?

Kelsey Cummings kgc at sonic.net
Wed Jul 16 11:06:05 PDT 2003

We've got a 5.1 box that we are using to play around with vinum and fcal.
It's a dual PIII-800, gig of ram, etc.

The Qlogic 2200 has 2 old NetApp FC8 shelves on them, with 14 disks.  Each
one of these disks is able to do a sustained 17MBs in sequential IO.
However, when all disks are accessed at once sustained I/O drops to ~1-4MBs
per device, or ~28MBs total for all devices together.  We see the same problem
with vinum, stipping all 14 disks together results in ~28MBs, which is the
same as what's gotten with 2, 4, 6, 8, .. disks.  During these tests the
box is responsive, CPU ultilization is minimal, etc.

We don't have much experience with fcal here but this doesn't make alot of
sense to us.  It would appear that the controller or loop is getting
staturated at only 28MBs? Can anyone shed some light?

We've just be using dd (single and multiple processes) to test the
sequential IO throughput. 

Kelsey Cummings - kgc at sonic.net         sonic.net
System Administrator                    2260 Apollo Way
707.522.1000 (Voice)                    Santa Rosa, CA 95407
707.547.2199 (Fax)                      http://www.sonic.net/
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