How to increase the size of the disk of a Windows 8.1 Virtual Box VM running in OSX

Question

Host OS: OSX El Capitan Guest: Windows 8.1

I created a virtual box VM with a 25GB disk. I install Windows 8.1 and everything was working great.

Then I decided to install Visual Studio, and before the installation could complete, I've run out of space.

Is there any way to resize the disk without having to reinstall the OS or abort the installation (having to download VS all over again ?)

If there isn't a way to resize without aborting the install, how do I do it ?

Answer 1

If you want to increase the size you would need to use the following command:

First go to the path of virtual box using CMD (Command Prompt)

cd “C:\Program Files\Oracle\VirtualBox”

Now you can resize the VDI file using the same CMD (Note this doesnt work for a FIXED disk file)

VBoxManage modifyhd <absolute path to file> --resize <size in MB>

e.x I have 10GB disk size and I want 20GB disk size. I first go to the path and then type in and enter the following command:

VBoxManage modifyhd <absolute path including the name and extension> --resize 20480

A tutorial with images can be found here

Answer 2

Open terminal, and type

VBoxManage modifyhd PATH/TO/YOUR_DISK.vdi --resize SIZE_IN_MB

For example, to resize win_virtual_disk.vdi from home dir to 30 GB you would type:

VBoxManage modifyhd VirtualBox\ VMs/Win/win_virtual_disk.vdi --resize 30000

Windows will not recognize the new disk size. Start the virtual windows image, and open Disk management tool. There, right click on your partition, and select Extend. Just press Next until done.