ESXi provides the ability to use raw device mapping (RDM) as a method to provide a VM with direct access to a LUN on a Fibre CHannel or iSCSI storage device. RDMs are useful should you have to share a LUN with a physical server or have SAN utilities running in the VM that will be able to access the LUN directly. You can also use an RDM to provide a VM direct access to a local SATA drive that is co