How to increase Virtualbox disk size in 9 easy steps

I work mostly on a Mac, but from time to time I get projects for Windows OS. I have Windows 8 virtual machine that I run under Virtualbox whenever I need to work on Windows.

Today, I needed to install Visual Studio in Windows 8 and it warned me that I would need 9 GB free disk space in order to do the installation. I opened the windows explorer and checked the amount of free disk space I have –

As you can see, I only had 8.94 GB free. I needed to somehow increase the disk size. So, I went to Google. I found many blogs on this subject and all have the same suggestion – delete all the snapshots and then issue the following command from the directory where your VDI file is located –

VBoxManage modifyhd YOUR_HARD_DISK.vdi --resize SIZE_IN_MB

So, if you have no snapshots or you don’t mind deleting all the snapshots, that’s all you need to do!

But, I don’t want to delete the snapshots. I take snapshots often, and can’t risk loosing any of my work. If you are in similar situation, keep reading.

STEP 1 – Open Virtualbox

Open Virtualbox and select the machine that needs the disk size to be increased –

STEP 2 – Select “Clone…” option

Select “Clone…” option from “Machine” menu and give it a new name. You can also leave it to default and change it later, then click “Continue” –

STEP 3 – Select Clone type

Select Clone type to “Full clone”, then click “Continue” –

STEP 4 – Select Snapshots

Select Snapshots to “Current machine state”, then click “Clone” –

Wait for the clone process to finish –

Once the clone process finishes, you will see the new virtual machine listed under Virtualbox –

STEP 5 – Increase the disk size for the new cloned machine

Issue the VBoxManage command I mentioned above, from the directory where your VDI file is located –

$ cd "Virtualbox VMs/Windows 8 (64 bit) Clone"
$ VBoxManage modifyhd "Windows 8 (64 bit) Clone.vdi" --resize 40000

I wanted the disk size to be increased to 40GB. You may want a different size, so, change the above command accordingly.

STEP 6 – Run new cloned machine

Run the new cloned machine.

If it needs, reboot it to get the new size of the hd.

You will notice, that even after we increase the disk size, Windows is still reporting the same old smaller size –

This is because the disk partition size does not automatically grow with the disk size. We will need to increase the disk partition size.

STEP 7 – Open “Disk Management”

Open “Disk Management”. You will notice “unallocated” space on the disk –

STEP 8 – Increase partition size

Select the disk that needs to be expanded (C: drive in my case), then from Action menu, select “All Tasks”, then select “Extend Volume”. The “Extend Volume Wizard” window will open, click “Next” –

In the following screen click “Next” –

In the following screen click “Finish” –

Now, you will be back in the “Disk Management” window with the partition expanded to the size you wanted –

STEP 9 – Check the new disk size in Windows explorer

Open Windows explorer and go to “My Computer”. You will see the disk size is now increased –

That’s it! Hope you find this tutorial useful.

Posted 29th December 2013 by