you can extend the space of your existing virtual hard disk by executing the following command:
“C:\Program Files\Oracle\VirtualBox\VBoxManage.exe” modifyhd OldDisk.vdi –resize 51200
51200 MB / 1024 MB => 50 GB
previously my virtual hard drive size was 25 GB and i just extended the same to 50 GB.
Upon that login to your virtual machine and then right click “My Computer” and select “Manager”. Then “Disk Management”. You will see some new spaces added after the C or whatever the corresponding drive. Then right click the corresponding drive and select “Extend Volume”. Follow the wizard and its done.
Note: VBoxManage modifyhd “D:\ISDev\myVDI.vdi” –resize 307200