18 months ago we did not have the Auto Failover; did you send the logs to support so we can see if there are areas that we can investigate?

Others are getting respective performances from posts below to compare - there are more but here is just a small few.

http://forum.open-e.com/showthread.php?t=1392
http://forum.open-e.com/showthread.php?t=1319 (look at the "SQLIO test in iscsi mode" tests)

In the test.log what is the hdparm for sdx?
Any dropped packets for the NICs - look in the same log file for ifconfig -a.

Try changing the following in the iSCS Target settings from Console (CTRL + ALT + W - Tuning options..)

maxRecvDataSegmentLen=262144
MaxBurstLength=16776192
Maxxmitdatasegment=262144
maxoutstandingr2t=8
InitialR2T=No
ImmediateData=Yes