RDM High-Level Cover VMware vSphere RDM or Raw Device Mapping is the method to remove levels of abstraction from the storage presented to vSphere VMs. RDMs are used to meet use cases and could be considered a deviation from the ‘normal’;. When creating an RDM, there are two options; Virtual and Physical. A Virtual RDM provides some level of storage abstraction. Physical does not, the full capabilities are visible by the VM.

I’;ve been having some issues with the conversion of a VMDK to a Physical RDM. This is a request from a client, as the storage and backup vendor has stated that there are advantages to doing this. Not something I have done before, but nothing wrong with that. I found the KB article with ease: https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=3443266 Steps looked straight forward, get the identifier and power down the server, run the commands.