All the answers for this question deal with base drive, but most of my VMs are snapshots, nothing else, so it seems none of the solutions actually work.
I tried filling it with zeros with SDelete, but that just took the file from being 35GB to 80GB, nothing I do shrinks the file; modifyhd -compact and modifymedium –compact show the whole progress bar, but don’t actually do anything. Now I have a massive 80GB file when I just wanted to shrink the drive.
CloneVDI just says “source disk is not a recognized vdi file format”
Is there a way to convert the snapshot to a main drive?
for clarity: The VM I am trying to compact was created as a full clone of a linked clone, which seems to lock it into being only snapshots; this is likely where the issue stems from. For now I will just recreate my VMs as full clones from the base instead of using linked clones as intermediates.