minimize size

This plugin can be used to reduce the size of the resulting image. Often virtual volumes are much smaller than their reported size until any data is written to them. During the bootstrapping process temporary data like the aptitude cache is written to the volume only to be removed again.

The minimize size plugin employs three different strategies to keep a low volume footprint:

  • Mount folders from the host into key locations of the image volume to avoid any unneccesary disk writes.
  • Use zerofree to deallocate unused sectors on the volume. On an unpartitioned volume this will be done for the entire volume, while it will only happen on the root partition for partitioned volumes.
  • Use vmware-vdiskmanager to shrink the real volume size (only applicable when using vmdk backing). The tool is part of the VMWare Workstation package.


  • zerofree: Specifies if it should mark unallocated blocks as zeroes, so the volume could be better shrunk after this. Valid values: true, false Default: false optional
  • shrink: Whether the volume should be shrunk. This setting works best in conjunction with the zerofree tool. Valid values: true, false Default: false optional