Fix the inability of increasing hard disk space in Windows 10 virtual machine

Symptoms

• I upgraded from Windows 7/8 to Windows 10 and cannot increase the size of my virtual machine disk.
• After I increased the hard disk space by following KB 113972, the Windows disk size still remains the same as it was before increasing it in File Explorer.
• If I open Disk Management ( Start button > type diskmgmt.msc > hit Enter (Return) ), I see that the last partition on the disk has been increased instead of the C:\ partition:
  
  

Information

Parallels Desktop increases the space of the last partition in a list. This is a default Windows behavior. To increase the size of a desired partition, you should use the Diskpart program.

Solution

NOTE: Before proceeding with the instructions below we highly recommend you creating a snapshot for data safety purposes.

To add space to the C:\ partition you need to remove the last partition that was extended by Parallels Desktop:

1. Right-click Start button, then click Command Prompt (Admin).
   
   or
   
   Click Start button and type Command Prompt then right-click on the suggested item Command Prompt > select Run as administrator.

2. Open the DISKPART utility by executing the following command:

   diskpart
   

   

3. Navigate to the required disk:

   list disk
   select disk <#>
   

   where <#> is the required disk number:

   

4. Navigate to required partition and remove it:

   list partition
   select partition <#>
   delete partition override
   

   where <#> is the number of the Recovery partition:

   

5. Navigate to the required volume and extend it:

   list volume
   select volume <#>
   extend
   

   where <#> is the C:\ volume number.

6. When the operation is finished, the following message will be displayed: DiskPart successfully extended the volume.

   

7. To make sure the operation was completed successfully, open File Explorer in your Windows virtual machine and check the size of the C: partition.