CREATE VMDK FOR ENTIRE DISK
 
IN LINUX
1. Run the command: sudo fdisk -l
2. You'll see a listing of the partitions.
3. Make note of the desired drive in the format of dev/sda, dev/sdb, etc.
4. Creating the VirtualBox Hard Drive with this command:
      VBoxManage internalcommands createrawvmdk -filename
      "</path/to/file>.vmdk" -rawdisk /dev/sda
 
IN WINDOWS
1. Open Disk Management
2. You'll see the associated drive numbers on the left.
3. Identify the drive numbers as PhysicalDrive0, PhysicalDrive1, etc.
4. Creating the VirtualBox Hard Drive with this command:
      VBoxManage internalcommands createrawvmdk -filename
      "<\path\to\file>.vmdk" -rawdisk \\.\PhysicalDrive#