How to compact VirtualBox's VDI file size?
On guest OS or VM
dd if=/dev/zero of=/var/tmp/bigemptyfile bs=4096k ; rm /var/tmp/bigemptyfile
sudo poweroff
On Host OS
VBoxManage modifymedium \
"/media/sibunglon/Data/VirtualBox VMs/Local Develoment/dependency/dependency.vdi" \
--compact