We have performance problems with a similar configuration:
DL380 G7's vSphere 4.1 U3
CN1000Q (10GB HW iscsi)
NetappFAS 2240's
HP A5800 as our storage switch for connectivity between VM hosts and Netapp storage
We've tried the 10GB converged adapters as HW iscsi, SW iscsi, and totally swapped out the the 10GB cards with 1GB HW iscsi cards.
We're in the process of replacing the A5800 with a different 10GB switch.
Which code version is your Netapp FAS2240?
We're at 8.1.1 7-mode for our production storage.
Have you been able to resolve your problem?
Thanks