Run disk cleanup. It is normally down to the Windows error reporting files and C:\Windows\Temp. Delete and empty them respectively. The former should be turned off via Group Policy and cleared on a weekly basis by the “Windows disk cleanup” scheduled task. The latter is cleared by a batch file which runs on startup and is in the startup folder of the administrator login; the administrator login is used on a monthly basis to install operating system updates in the respective pooled VMs.
If the above fails:
1. Ensure system restore is turned off and paging file is disabled. Defragment drive. Also run “powercfg /h off” in elevated command prompt. Restart
2. Shrink through disk management. If not possible, use the free partition tool (\\172.17.8.7\public\\IT\Partition tools) to shrink.
3. Shrink and compact vhdx
4. Increase vhdx
5. Increase through disk management
6. Check in VDI settings that current file size use is not back where it originally was.
7. Re-enable paging file and remove the partition program
8. Disable all error reporting.
9. Batch file to delete contents of c:\windows\temp as part of the master image. Ensure it is set to run at administrator login – in the startup folder. Run the batch file.
10. Ensure Windows Disk cleanup and disk defrag set to run automatically every week with the highest privileges regardless of whether the user is logged on: http://www.thewindowsclub.com/automate-disk-cleanup-utility-windows . Run the former.
11. Final restart