How to add new harddrive to VirtualBox virtual machine

You can attach new storage to your Virtualbox virtual machine (VM) after it's already been created. This storage can either be from virtual hard disks of supported format commonly used by other virtualization platforms such as VMware or QEMU or create a new one.

The new storage can be attached to either the IDE or SATA controller, depending on your preference and requirement.

1. Launch VirtualBox.
2. Make sure the VM is powered off.
3. Right click on the VM from the list and click on Settings.
4. Go to Storage tab.
5. Select which controller you want to add the disk to and click on the Add new storage attachment button.
6. Select Hard Disk from the list.
7. Click Add to add existing disk.
8. Select from existing disk and click Open.

   Supported format includes VMDK (.vmdk), VDI (.vdi), VHD (.vhd), Parallels (.hdd), QED (.qed), QCOW (.qcow, .qcow2) and VHDX (.vhdx)

9. Click Create to create new hard disk.
10. Choose type and click Continue.
11. Choose disk allocation type and click Continue.
12. Choose the size of hard disk, select location and filename (optional) and click Create.
13. Select added or created hard disk from Not Attached section and click Choose.
14. Click OK.
15. Launch the VM to configure the newly added hard drive on the operating system level.