I have tried that a few days ago. It works with vMotion when connected to multiple ESX hosts

Since the MD3220 DAS is supported with ESXi per the VMware HCL http://www.vmware.com/resources/compatibility/search.php and the Dell | VMware HCL http://www.delltechcenter.com/page/VMware, once you configure and setup of the MD3220 as shared storage for multiple ESXi hosts, it will support vMotion between the connected ESXi hosts. Please refer to the MD3220 tech guide book for multi-host config guidelines especially page 38 - http://www.dell.com/downloads/global/products/pvaul/en/powervault-md3200-md3220-technical-guidebook-en.pdf