At some point you might need to extend the disk space on a Windows Server Core and this can be done using Powershell.
The Powershell command Get-Volume will display information about the disk (Drive Letter, Size, Size Remaining etc).
You will have to add space from your hypervisor and then use diskpart to rescan the volume to make the virtual machine aware of the space added.
Next you will need to create a Powershell variable and bind the maximum volume size to it.
After you create the variable you need to run the Resize-Partition command in order to increase the disk space.
Now if you will run Get-Volume you’ll see that disk space was increased.