Deploy NVMe Storage Devices using Discrete Device Assignment
Applies to: Windows Server 2022, Windows Server 2019, Microsoft Hyper-V Server 2016, Windows Server 2016
Starting with Windows Server 2016, you can use Discrete Device Assignment, or DDA, to pass an entire PCIe Device into a VM. This will allow high performance access to devices like NVMe storage or Graphics Cards from within a VM while being able to leverage the devices native drivers. Please visit the Plan for Deploying Devices using Discrete Device Assignment for more details on which devices work, what are the possible security implications, etc. There are three steps to using a device with DDA:
- Configure the VM for DDA
- Dismount the Device from the Host Partition
- Assigning the Device to the Guest VM
All command can be executed on the Host on a Windows PowerShell console as an Administrator.
Configure the VM for DDA
Discrete Device Assignment imposes some restrictions to the VMs and the following step needs to be taken.
- Configure the “Automatic Stop Action” of a VM to TurnOff by executing
Set-VM -Name VMName -AutomaticStopAction TurnOff
Dismount the Device from the Host Partition
Locating the Device's Location Path
The PCI Location path is required to dismount and mount the device from the Host. An example location path looks like the following:
"PCIROOT(20)#PCI(0300)#PCI(0000)#PCI(0800)#PCI(0000)". More details on located the Location Path can be found here: Plan for Deploying Devices using Discrete Device Assignment.
Disable the Device
Using Device Manager or PowerShell, ensure the device is “disabled.”
Dismount the Device
Dismount-VMHostAssignableDevice -LocationPath $locationPath
Assigning the Device to the Guest VM
The final step is to tell Hyper-V that a VM should have access to the device. In addition to the location path found above, you'll need to know the name of the vm.
Add-VMAssignableDevice -LocationPath $locationPath -VMName VMName
After a device is successfully mounted in a VM, you're now able to start that VM and interact with the device as you normally would if you were running on a bare metal system. You can verify this by opening device manager in the Guest VM and seeing that the hardware now shows up.
Removing a Device and Returning it to the Host
If you want to return he device back to its original state, you will need to stop the VM and issue the following:
#Remove the device from the VM Remove-VMAssignableDevice -LocationPath $locationPath -VMName VMName #Mount the device back in the host Mount-VMHostAssignableDevice -LocationPath $locationPath
You can then re-enable the device in device manager and the host operating system will be able to interact with the device again.
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