This is an active/passive array; each virtual disk is owned by a single controller. Therefor only the paths to the controller that owns the virtual disk in question will be able to process I/O; the paths to the non-owning controller are there for failover. This is why using 2 or more virtual disks is recommended so that each controller can own it's own virtual disks (and the other controller for it's failover). Active/Active SANs put you in a completely different price range than an MD3600i. Just FYI; if you check the MD3600i support matrix ( ), you'll see that Qlogic HBAs aren't supported. This means that if you have connectivity issues, there is no support from Dell on these HBAs. You can check the support matrix to see which options are available that offload iSCSI. 
Dual controller MD3600i with separate subnets (as per manual), connecting via separate isolated switches to two separate HBAs in ESX 4/5What am I supposed to see (have) with multipath working correcly?Active (I/O) - Active (this is what I have showing currently)orActive (I/O) - Active (I/O) (I believe it should be that condition)on each controller for each target (LUN)The manual states:Increasing Bandwidth With Multiple iSCSI Sessions The PowerVault MD3600i Series storage array in a duplex configuration  supports two active/active asymmetric redundant controllers. Each  controller has two 10G Ethernet ports that support iSCSI. The bandwidth  of the two ports on the same controller can be aggregated to provide  optimal performance. A host can be configured to simultaneously use the  bandwidth of both the ports on a controller to access virtual disks  owned by the controller. The multi-path failover driver that Dell  provides for the MD3600i Series storage array can be used to configure  the storage array so that all ports are used for simultaneous I/O  access. If the multi-path driver detects multiple paths to the same  virtual disk through the ports on the same controller, it load-balances  I/O access from the host across all ports on the controller.There is no driver for ESX, so how would one configure it?I am NOT using the targets (LUN) for VMFS, but RDM to my VM OSThanksSeb
Dell MD3600i & multipath with vSphere 4/5