Hi,
At the recent kolla virtual PTG [1] we had a good discussion about adding support for multiple nova cells in kolla-ansible. We agreed a key requirement is to be able to perform operations on one or more cells without affecting the rest for damage limitation. This also seems like it would apply to upgrades. We're seeking input on ordering. Looking at the nova upgrade guide [2] I might propose something like this:
1. DB syncs 2. Upgrade API, super conductor
For each cell: 3a. Upgrade cell conductor 3b. Upgrade cell computes
4. SIGHUP all services 5. Run online migrations
At some point in here we also need to run the upgrade check. Presumably between steps 1 and 2?
It would be great to get feedback both from the nova team and anyone running cells Thanks, Mark
[1] https://etherpad.openstack.org/p/kolla-train-ptg [2] https://docs.openstack.org/nova/latest/user/upgrade.html