additionally, i am encountering an error when trying to create an external snapshot with virsh for additional “secondary” disk images which are used for persistent storage. i expected this and will research it more.
an alternative method for creating snapshots for additional disks, assuming one would want to do that (i think creating backups on the additional disk makes more sense), is to create thin provisioned images for additional disks as well. while i think it is easier to keep all the files for additional disks confined to one file, i could just as easily create an additional “move your disks to another computer” script which could export the appropriate vm related xml, commit the most recent thin provisioned image to the backing file, and compress it to a tar file, ideally with a script to run that could export it into a kvm instance later. it would be similar to exporting an “ova” file from an existing virtualbox virtual machine.
so, there may end up being 3-4 tools here if anyone thinks it is worth it (deballoon+snapshot script, snapshot only script, snapshot restore and management script, backup/“copy to another computer” script.).