10Gb NIC Teaming with pair of Nexus switches

I have not seen tests with Nexus switch on the Cisco switch specifically. The speeds should be closer to the 10Gbps than the 88Mbps you are saying in the post.

Have you tried the 4200 with a single 10GE interface to see if you were able to get any faster speeds? (hopefully ruling out the LACP)

What is on the other end talking to it?
What teaming mode are you using right now? LACP should be safest bet.

If using ESX, this makes a huge difference: viewtopic.php?f=118&t=65374

Right now I'm trying to get Veritas Backup Exec 2010 to use the ReadyNAS as a disk target (a battle all its own)....

But, that ESX article is EXTREMELY helpful, thank you. That would have been my next step after the backups are working.

Turning off teaming has helped but performance and reliability are still question marks because the RALUS agent is a piece of (fine engineering)....

Backup job just keeps slowing down and then timing out, but I'm not seeing any errors on the 10gb interface anymore.