Resizing VHDX in Windows 2012 using PowerShell

In order to be able to resize the VHD you need to follow few steps first. You can do that from the GUI, however in my experience your best rate of success is to use the PowerShell. Please note that this apply only to Hyper-V in Windows 2012 and above, there isn’t a process available yet for the previous versions of Hyper-V

Below are the steps of how to do that, just as an explanation in order to be able to resize the VHD we need to resize the partition inside the Virtual machine, as to let the vhd file know that this space is free and its safe to remove it.

The command below will provide all the steps required to resize the vhd, however it requires the server to be shut down. The steps are as follow:

1. Shut down the VM
2. Mount the VHD using mount-vhd command with command line as follow:

mount-vhd path\drive.vhdx -passthru | get-disk | get-partition | get-volume

This command will provide you with information of what drive letter the partitions inside vhdx files have been assigned as well as the size details (remember that from Windows 2008 and up the system create a 100-300MB partition on the main drive used in booting process, don’t resize it)

3. The next command is resize-partition, that is to resize the size of the partition inside the vhdx to the size you want it to be

resize-partition –driveletter D -size 40GB

-driveletter is the drive letter we get from the first command, and –size is the size to what we want to shrink the partition to.

4. Next we will dismount the vhd using dismount-vhd:

dismount-vhd path\drive.vhdx

5. The last command is actual resizing of the VHD, to do that we use: resize-vhd command:

resize-vhd path\drive.vhdx -ToMinimumSize