Thank you for the link. Does this mean that I can change the "Storage format" field from raw to qcow2 and continue to use the VM ? That storage format option was not available within the Unraid VM settings page when I created it,
Actually, I just answered my own question when attempting to change it.
So it looks like I would need to have created the VM from within virt-manager to start with and use a qcow2 storage format in order to use the snapshot manager. Is that how you use it?