I manage a lot of Ubuntu machines, many physical, many virtual.
Backup as a general concept is pretty simple, but backup of entire systems tends to get murky. I'm familiar with virt-p2v, but that tends to require individual attention to a system when you want to migrate it. The same is true with migrating disk images (qed, vmdk, LVM volumes, et cetera.)
The closest I've found has been Acronis Backup and Restore, which runs an agent on each machine (bare or guest) and communicates with a central server and handled various conversion aspects like converting disk UUIDs and MBR-to-GPT conversions as part of the restore process.
Unfortunately, Acronis is proprietary and wildly expensive if you want these features for two home systems and a dozen VMs.
Are there any good solutions I could put in place that take backups in a way that largely ignores the state a restore would be done in? That is, machines are regularly backed up in an automated fashion so that when need arises, it can be quickly restored to a target machine - even if this target machine is now a VM when it was previously bare? (Or the other way around?)