As a cloud operator, in case of failed update I want to revive whenever it is possible and continue in the process so that I don't have to rollback and start the whole procedure over again.
Service update should be idempotent, we are trying to achieve a goal: "If updates fail, I want to re-run update command, which will revive the procedure and ends the process (this time hopefully) successfully."
https://blueprints.launchpad.net/tripleo/+spec/undercloud-backup-restore
Need a associated test plan for QE if possible.