
According to nova rolling upgrade process [1], online_data_migrations should run once all the services are running the latest version of the code and were restarted. With that, we should move online migrations after handlers being flushed, when all services are restarted. At the same time, nova-status upgrade check must run before services are restarted to the new version, as service restart might lead to service breakage if upgrade check fails [2]. It makes no sense to run upgrade check when upgrade is fully finished. [1] https://docs.openstack.org/nova/latest/admin/upgrades.html#rolling-upgrade-process [2] https://docs.openstack.org/nova/latest/cli/nova-status.html#upgrade Change-Id: Ic681f73a09bb0ac280c227f85c6e79b31fd3429a