Urbackup wont do image backup on linux anyway. And at 4tb, i don’t think that s what you want (even with other backup solutions, or they’d have to be very good/expensive to that smartly).
You could hack that into urbackup using scripts, because urbackup scripts can backup anything that comes from stdout.
It’s better to backup databases as dump (aither backup the file our use a script and dump to stdout then let urbackup scripts capture that),
Simply backup files as files
Setup some good deploy tool, so that you can restore a full computer using your deploy tool, then the files/db inside it.
Remember that for example, you can t dump an ext4 filesystem, you’d need to put it into an lvm and then capture the lvm for it to be consistant. And thats not a urbackup limitation, that comes from ext4 itself.