Getting error trying to create VMDK Pass-through (RDM) on ESXi 6

robklubs used Ask the Experts™
I'm trying to create an RDM passthrough VMDK file with vmkfstools via Putty (SSH) on a brand new ESXi 6 install. There are two datastores attached the new ESXi host. The one that I'm trying to get this VMDK created on is active and already hosting the vCenter appliance.

Here is the syntax of what I'm getting. I zeroed out the SN's and some other information:

login as: root
Using keyboard-interactive authentication.
The time and date of this login have been sent to the system logs.

VMware offers supported, powerful system administration tools.  Please see for details.

The ESXi Shell can be disabled by an administrative user. See the vSphere Security documentation for more information.

[root@esxisuper:~] vmkfstools -z /vmfs/devices/disks/t10.ATA_____Samsung_SSD_850_EVO_1TB_________________XXXXXXXXXXXXX /vmfs/volumes/SSD_Sam950ProNVME_500GB/ET03PT/ET03PT.vmdk

Failed to create virtual disk: The specified device is not a valid physical disk device (20).

I know the directory (/vmfs/volumes/SSD_Sam950ProNVME_500GB/ET03PT/) in which I am trying to create the VMDK exists as I created a VM (with no HD) from vCenter (web client) with no issues. The VMX and VMSD are both present in that directory. The device ID for the HD I'm trying to use all looks correct and there are no errors on that side of things. There is already a Win10 install on that HD that I'm trying to passthrough.

Let me know if I should provide any more information. I'm just not sure what I'm missing here.

Thanks in advance for your help!
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Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

Although technically *NOT SUPPORTED*, please check my EE Article, when I demonstrated this for 5.1.

HOW TO: Add Local Storage (e.g. a SATA disk) as a Raw Disk Mapping (RDM) or Mapped RAW LUN to a virtual machine hosted on ESXi

So you are trying to passthrough, because there is already data on the SSD ?

What are going to do with the Win 10 install ?


Correct, I am trying to passthrough as there is already data on the SSD. The purpose is twofold: (1) I'm going to want to go beyond 2 TB at some point and (2) I'd like to be able to take the drive with me (remove from host, add to laptop) when I travel. The passthrough HD is going to hold my primary workstation. Well, at least in theory it will.

And yes, I did see you're article* and followed that as well in my troubleshooting steps. I get a slightly different error when I try your syntax, which uses the -r switch:

Failed to create virtual disk: The destination file system does not support large files (12).

*Your articles are ubiquitous and without peer on all things VMware on EE. I've lost count on how many times I have referenced them. And you've actually helped me out before on a alarm issue and pointed me towards Solar Winds (which I'm planning on implementing on this new ESXi install).  Thanks again!
VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
Since 5.5, VMware ESXi now supports virtual disks larger than 2TB.

Also RDMs cannot be used as OS BOOT drives, they are only used for data.

As this was originally never officially supported, it's possible vmfstools has been changed, or you have the incorrect disk reference.

Thanks for your kind words about my articles.


Thanks! I'll keep plugging away at it.


Got it! You were correct, Andrew. It was an incorrect disk reference.

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