My bad Yousfi, I tested on Windows 7 while the MSFT_PhysicalDisk class documentation specifies:

Minimum supported client: Windows 8 [desktop apps only]
Minimum supported server: Windows Server 2012 [desktop apps only]

And, as I did not specify my OS in the question description, my double bad!

>The code i gave was tested on my windows 10 fall creator version 1709 and works as well.
>read this for some previous versions : https://msdn.microsoft.com/en-us/library/aa394603(v=vs.85).aspx
>good luck!