Any tweaks for iSCSI on a Mac? Slow transfers

I’m running AJA System Test and I’ll watch the progress bar fly during each test while I’ll have a transfer in the 70’s MB/S and then about 2/3rds of the way across, it will hesitate for a sec and the transfer rate will drop to 20 MB/s or lower. I’m regularly getting single digit read speeds as well.

Is there any way to keep the transfer rates in the 70’s or 60’s?

I’ve got a drobopro with 8 2 TB hard drives. 4 are 5400 WD green drives and 4 are 5900 seagate drives. I’m running DD v2 as that gives the best performance. I’ve tried DD 1.7.3 and 1.8.4 as well. I’ve done the proper uninstall, reboot, install, and reboot procedure.

OS X 10.6.7 on Mac Pro

Mine was flying (80+ MB per second) when I set up Jumbo Frames on the host ethernet card. I run 8x2TB WD Green Power drives.

My Pro is connected directly to the second ethernet interface on my Mac Pro with Cat 6 cable.

EDIT: Just read that Jumbo Frames are not supported with the Drobo Pro.

Just for the heck of it I turned my eth0 port on my Mac Pro to Auto and 1500 instead of 9000 and I am getting a solid 75MB (megabyte) per second transfer to my Drobo Pro.