On Linux Host: Shut down the VM and run:
Inside Windows: Run Defragment and Optimize Drives -> Optimize (This allows the guest to mark free space). Windows 10.qcow2
-drive file=Windows 10.qcow2,format=qcow2,if=virtio,aio=native,cache.direct=on For libvirt (virt-manager), edit the VM XML: On Linux Host: Shut down the VM and