[ovirt-users] Attaching ISO to hosted engine for OS upgrade

I'm working on upgrading an oVirt 3.5 setup. The physical hosts are running CentOS 7, but the hosted engine is CentOS 6. The upgrade notes are "back up the engine, upgrade/reinstall the OS, then restore", but I can't see how to actually install CentOS 7 on the engine. Am I supposed to re-run "hosted-engine --deploy"? Wouldn't that try to re-register the physical hosts, or can I interrupt it to restore the backup? Or, is there a way to just attach an install ISO to the engine VM and boot from that? -- Chris Adams <cma@cmadams.net>