Hello Todd, Yes only one controller can access the lun at a time.  This is done to prevent corruption from both controller reading & writing to the same VD at the same time.  What you will need to do is to get a switch so that you can add multiple connections to the same nic on the controller for the MD & it will allow you to do what you are trying to do. Let us know if you have any other questions.
Hi, I currently have an MD3200i configured with 4 hosts, directly connected without using switches.  I'm doing this as per a diagram provided in the Dell manual.  each server has 2 NICs and 1 NIC from each server goes to each of the 2 controllers on the SAN.  This provides redundancy spread across multiple NICs, cables and SAN controllers while eliminating the switch point of failure.  I'm successfully using MPIO to allow me to lose a link and still keep the host up on the other link.  Hyper-V live migration works great as well.  My concern is that I cannot get both links on each server to go "Active", it'll only do one at a time, so I'm not getting the performance benefits of MPIO.  In doing research I think this is due to the virtual disk only being owned by one controller, and the NIC on that controller is the only one that can go active, the other NIC is put into standby since it's controller doesn't currently own the virtual disk.  Is that correct?  And if so is there any way to get both links to go active while still spreading my hosts over both controllers?  Or do I need to involve switches so the hosts have multiple connections to each controller?  Thanks, Todd
MD3200i MPIO