====== Virtualbox ======
  * performance: https://askubuntu.com/questions/190330/how-do-i-improve-the-performance-of-my-virtualbox-guest
  * image: https://www.osboxes.org/ubuntu/#ubuntu-16-04-info
  * convert vdi qcow2: qemu-img convert -f vdi -O qcow2 vm.vdi vm.qcow2

  * https://daily-tux.org/build-with-packer-qcow2-images-e-g-for-openstack/
===== Performance =====
Base memory: 4096 Mb (8192 Mb total host memory)

Processor: 6 CPUs (of host 6 CPUs)

PAE/NX: Enabled

VT-x/AMD-V: Enabled

Nested Paging: Enabled

Display

Video memory: 128 Mb

3D Acceleration: Enabled

2D Acceleration: Enabled