I did some more research and isolated traffic to just data transfer. Using a free tool (Disk Thruput Tester) that is normally used to determine read/write to disk, I arrived at a wide performance spread:
Sequential write results (3906 Mb in 3906 chunks): 9.1 MB/s to 37.9 MB/s
Sequential read results (3906 Mb in 3906 chunks): 16.2 MB/s to 66.3 MB/s
Random access results (3906 Mb in 3906 chunks): 6413.8 MB/s to 6545.8 MB/s
A second PC had similar results. The range is from far below the performace of a USB 2.0 device to about 1/3 above.
Any idea why the range is so wide (the tests were done on and isolated segment with no other traffic)?
I am satisfied with performance on par with ISB 2.0, but would like to tune whatever I can. With RAID 5 I have three heads writing, which should increase per formance for sequential activity. I am wondering whether the storage processor is the bottleneck?!!