It's like SpaceHogs but the files are moved once to a zone (spacehogs zone or a new zone) and then aren't moved by the standard scripts unless absolutely necessary. This is to accommodate virtualization disks that can be quite large and often has static size, and takes forever to move/defragment due to their size.
With the current setup they are considered spacehogs and can be moved/defragmented with some of the scripts each time the scripts are run depending on how other files has been changed/added/deleted. It's far more efficient to move/defragment them once and leave in place, ie. if a file belongs to the MonolithFiles-collection it's moved and defragmented the first time to the correct zone and then it's ignored unless we specifically want to defrag/move it. It's possible that the only way to accomplish this is to add another script that only defragment/moves these files and all other scripts ignore them.
The definition of a monolith file may be > 1GB for example or matching extensions from popular virtualization softwares and disk-images, for example *.disk, *.vdi, *.dsk, *.iso, *.nrg etc. (List here: http://www.file-extensions.org/filetype/extension/name/disk-image-iso-binary-files
I know it's entirely possible to modify the supplied scripts so they handle this, but since virtualization are becoming more pervasive every day it might be wise to add this functionality to the scripts that get installe d by default.