[openstack-dev] [TripleO] State preserving upgrades working, next MVP selection?

Robert Collins robertc at robertcollins.net
Sun Jan 26 20:30:22 UTC 2014

So great news - we've now got state preserving upgrades actually
working - we can now upgrade a deployed cloud (with downtime) without
tossing away all the users valuable data. Yay. This isn't entirely
done as we have a couple of outstanding patches we're running early
versions of, but - still, it's time to pick a new focus.

So we need to pick the next step to focus on. In our roadmap we have:

MVP4: Keep VMs running during deploys.

This to my mind means two things:
 - VMs need to not be interrupted
 - network traffic needs to be uninterrupted

Now, as the kernel can be upgraded in a deploy, this still requires us
to presume that we may have to reboot a machine - so we're not at the
point of focusing on high performance updates yet.

Further consequences - we'll need two network nodes and two
hypervisors, and live migration. 10m (the times-two reboot time for a
server) is too long for the central DB to be down if we want
neutron-agents not to get unhappy as well, so we'll really need two
control plane nodes.

So I think the next MVP needs the following cards:
 - HA DB
 - HA APIs
 - rolling upgrades
 - nova live migration
 - neutron agent migration *or* neutron distributed-HA setup
 - scale the heat template to have 2 control plane nodes
 - scale the heat template to have 2 hypervisor nodes

as a minimum - are these too granular or about right? I broke the heat
template change into two because we can scale hypervisors right now,
whereas control plane scaling will need changes and testing so that we
only have one HA database created, not two non-HA setup in parallel

I'm going to put this into trello now, and will adjust as we discuss


Robert Collins <rbtcollins at hp.com>
Distinguished Technologist
HP Converged Cloud

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