Creating Large VirtualBox Disks on Windows

The VirtualBox GUI caps a new .vdi disk at 2TB, but that’s a limit of the interface, not the disk format itself. Using the command line you can create much larger disks, and in this guide we’ll make an 18TB dynamic .vdi on a Windows host to show how it’s done.

Step 1: Open Command Prompt

Open Command Prompt on your Windows host by searching for cmd in the Start menu and launching it.

Step 2: Go to the VirtualBox Directory

Change into the VirtualBox installation directory, which is usually the default below but may differ on your machine:

cd C:\Program Files\Oracle\VirtualBox

You can confirm you’re in the right place by listing the contents with dir and checking that VBoxManage.exe is there.

Step 3: Create the Disk

Now create the disk with vboxmanage. The size is given in megabytes, where 1TB is 1,048,576MB, so an 18TB disk is 18,874,368MB. Set the filename to wherever you want the disk to live:

vboxmanage createmedium disk --filename "F:\VMs\18TB.vdi" --size 18874368 --format VDI

This creates a dynamically allocated VDI, meaning the file starts small and grows as data is written, so it won’t immediately consume 18TB on your drive. Adjust the size figure to whatever you actually need.

One thing to be aware of with disks larger than 2TB: the guest OS will need to use the GPT partition scheme rather than MBR, and you’ll want to enable EFI in the VM’s settings before installing an operating system on it. If that causes any trouble with a fresh install, a reliable alternative is to attach this large disk as a secondary drive to an existing VM, through Settings and then Storage, and use it for data rather than the boot disk.

Related guides

• Converting VirtualBox .vdi to Proxmox VM using VBoxManage
• Automate Virtual Machine Startup in Windows