PowerCLI one liner to obtain RDM naa numbers from a vCenter datacenter

Launch PowerCLI and connect to a vCenter server:

Connect-VIServer vc01.vi.local

Then run the command below:

get-datacenter DataCenterName | Get-VM | Get-HardDisk -DiskType "RawPhysical","RawVirtual" | Select Parent,Name,CapacityKB,Filename,ScsiCanonicalName,DeviceName | export-csv C:\GetNAAs.csv

Open that csv file and the RDM naa numbers are there for your perusal.