VMware vSphere 4 gives us the ability to actively use multiple iSCSI paths to reach a single LUN. You will need to use vSphere Client, your iSCSI storage management tools, and an ESX command-line interface (such as ssh, RCLI or vSphere Management Assistant) to get it working. This procedure can be used to add up to eight iSCSI paths per datastore, provided each path uses a unique physical NIC and that each physical NIC has a corresponding NIC on the iSCSI SAN side. In other words, setting up more paths on the VMware side than your iSCSI SAN can actually accommodate would be pointless.
This tutorial assumes that you are familiar with vSphere Client and can find your way around. Read on beyond the break.