Some days ago I had the problem, that my windows VM in virtualbox got too small. Therefore I had to resize it. If you have no snapshots created yet for your windows virtualbox, it is quite easy to resize it. First of all you have to move into the directory where your virtualbox vdi file is located.
At my ubuntu host it is
cd ~/VirtualBox\ VMs/windows/
There I have the
winows.vdi and to resize it, we can use the
VBoxManage modifyhd windows.vdi --resize 50000
After that we just have to resize the disk in windows itself. Therefore we can use the really powerfull internal resize tool of windows.
To get to this utility, open up Control Panel, and type in partition into the search box.. you’ll immediately see the link show up:
In the Disk Management screen, just right-click on the partition you want to extend, and select “Extend Volume” from the menu. And surprise, surprise the disk is extended.