====== Compact VDI ======
===== Windows guest =====
  - Run defrag in guest
  - Download [[https://technet.microsoft.com/en-us/sysinternals/bb897443|SDelete]] from Sysinternals and run this || sdelete c: -z
  - Shutdown the guest

===== Linux guest =====
  - Run the following commands in guest: \\ **sudo dd if=/dev/zero** | **pv** | **sudo dd of=/bigemptyfile bs=4096** \\ **sudo rm -rf /bigemptyfile**
  - Or run theese commands: \\ **telinit 1** \\ **mount -o remount,ro /dev/sda1** \\ **zerofree -v /dev/sda1**
  - Shutdown the guest

===== Windows host =====
  - run: \\ "c:\Program Files\Oracle\VirtualBox\VBoxManage.exe" modifyhd c:\path\to\vdi\disk.vdi compact

===== Linux host =====
  - run: \\ vboxmanage modifyhd /path/to/vdi/disk.vdi --compact

===== OSx host =====
  - run: \\ VBoxManage modifyhd /path/to/vdi/disk.vdi --compact