How to Identify the virtual machines with Raw Device Mappings (RDMs) using PowerCLI

Open the vSphere PowerCLI command-line.
Run the command:

Get-VM | Get-HardDisk -DiskType "RawPhysical","RawVirtual" | Select Parent,Name,DiskType,ScsiCanonicalName,DeviceName | fl

This command produces a list of virtual machines with RDMs, along with the backing SCSI device for the RDMs.

An output looks similar to:

Parent                      Virtual Machine Display Name
Name                       Hard Disk n
DiskType                  RawVirtual
ScsiCanonicalName naa.646892957789abcdef0892957789abcde
DeviceName            vml.020000000060912873645abcdef0123456789abcde9128736450ab

If you need to save the output to a file the command can be modified:

Get-VM | Get-HardDisk -DiskType "RawPhysical","RawVirtual" | Select Parent,Name,DiskType,ScsiCanonicalName,DeviceName | fl | Out-File –FilePath RDM-list.txt

Identify the backing SCSI device from either the ScsiCanonicalName or DeviceName identifiers.