When creating an RDM for a virtual machine, it is necessary for ESX/ESXi to create an RDM pointer file for the virtual machine configuration file (VMX) to reference.
This issue can also occur when the RDM is a supported file size. For example, you may have a problem recreating an RDM pointer file on a datastore with a 1MB block size when the RDM itself is 100GB. An RDM pointer file to the same RDM may have resided in that datastore previously, but the datastore (LUN) had been deleted so that it could be freshly created.
The error occurs when trying to re-create the RDM pointer file because it is not able to access the LUN in question. A rescan restores LUN access and the RDM can then be added.
Ensure that the APD situation is resolved, and retry adding the RDM to the virtual machine. For more information, see Troubleshooting LUN connectivity issues (1003955).