Let me tell you a story about the last time I ran `yum upgrade -y` on my oVirt node at home without doing it in `screen`: I decided to upgrade my Fedora desktop

Let me tell you a story about the last time I ran `yum upgrade -y` on my oVirt node at home without doing it in `screen`: I decided to upgrade my Fedora desktop at the same time and rebooted after it finished not thinking twice about it, 5 seconds later I said "oh fuck" and prayed that the update on the server finished before I rebooted. It didn't. I then proceeded to spend the next 2-3 hours reinstalling CentOS on my server, re-configuring oVirt and re-importing all of my VM's from the store. Now, imagine an embedded device with a potentially flaky power source that could be interrupted in the middle of a system update - you really want to avoid that situation if at all possible. OSTree or Mender are a much better solution when you want an "all or nothing" upgrade, especially as they protect the system from FAILED updates and allow easy rollback.