[virtualbox] How to resize a VirtualBox vmdk file

Simply you have to follow the following steps:

  1. Power off your machine.
  2. Right click on virtual machine name > Settings > Storage
  3. Click on Controller : SATA > Add Hard Disk.
  4. Choose the new hard disk drive type size and hit create.
  5. Discard the machine state.
  6. Insert Ubuntu Live CD.
  7. Boot from ubuntu live cd.
  8. Open "gparted" (It's installed, not need to installation).
  9. Check if the system see your new created hard disk.
  10. Open Terminal.
  11. Type the following code.
  12. sudo dd if=/dev/sda of=/dev/sdb (The first is the old partition path, the second is the new partition path).
  13. Wait until its finish copying data (This step may take some time according to your host specs).
  14. After finish copying, return to gparted and select refresh devices.
  15. Select the new partition /dev/sdb it must be typical to the old one after doing dd command.
  16. It'll show the expanded space as unlocated data.
  17. Delete Swap partition/Extended partition.
  18. Right click on root partition /dev/sdb > Resize
  19. Allocate the whole space without swap allocation.
  20. Create new extended partition > Choose extended > Create
  21. Create new linux-swap partition > choose linux-swap > Create
  22. Now turn off your running machine.
  23. Right click on machine > settings > Storage.
  24. Eject ubuntu live cd.
  25. Right click on the old hard disk > remove attachment.
  26. Now you can start your vm from the newly created hard disk.
  27. Check the storage by enter df -kh command.
  28. It must show you the new size.

Congratulation, enjoy your free space.
This video will help you: https://youtu.be/ikSIDI535L0