[openstack-dev] [nova][neutron] Migration from nova-network to Neutron for large production clouds

Tim Bell Tim.Bell at cern.ch
Wed Aug 27 10:59:58 UTC 2014


> -----Original Message-----
> From: Michael Still [mailto:mikal at stillhq.com]
> Sent: 26 August 2014 22:20
> To: OpenStack Development Mailing List (not for usage questions)
> Subject: Re: [openstack-dev] [nova][neutron] Migration from nova-network to
> Neutron for large production clouds
...
> 
> Mark and I finally got a chance to sit down and write out a basic proposal. It
> looks like this:
> 

Thanks... I've put a few questions inline and I'll ask the experts to review the steps when they're back from holidays

> == neutron step 0 ==
> configure neutron to reverse proxy calls to Nova (part to be written)
> 
> == nova-compute restart one ==
> Freeze nova's network state (probably by stopping nova-api, but we could be
> smarter than that if required) Update all nova-compute nodes to point Neutron
> and remove nova-net agent for Neutron Nova aware L2 agent Enable Neutron
> Layer 2 agent on each node, this might have the side effect of causing the
> network configuration to be rebuilt for some instances API can be unfrozen at
> this time until ready for step 2
> 

- Would it be possible to only update some of the compute nodes ? We'd like to stage the upgrade if we can in view of scaling risks. Worst case, we'd look to do it cell by cell but those are quite large already (200+ hypervisors)

> == neutron restart two ==
> Freeze nova's network state (probably by stopping nova-api, but we could be
> smarter than that if required) Dump/translate/restore date from Nova-Net to
> Neutron Configure Neutron to point to its own database Unfreeze Nova API
> 

- Linked with the point above, we'd like to do the nova-net to neutron in stages if we can

> *** Stopping point for linuxbridge to linuxbridge translation, or continue for
> rollout of new tech
> 
> == nova-compute restart two ==
> Configure OVS or new technology, ensure that proper ML2 driver is installed
> Restart Layer2 agent on each hypervisor where next gen networking should be
> enabled
> 
> 
> So, I want to stop using the word "cold" to describe this. Its more of a rolling
> upgrade than a cold migration. So... Would two shorter nova API outages be
> acceptable?
> 

Two Nova API outages would be OK for us.

> Michael
> 
> --
> Rackspace Australia
> 
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