[Openstack-operators] Migration from openvswitch to linuxbridge

Robert van Leeuwen Robert.vanLeeuwen at spilgames.com
Wed Oct 1 06:09:40 UTC 2014

> To help people help you:
> - Are you running with ML2 plugin + ovs mechanism? (yes according to
> below details)
Currently we run without ML2 but since we run Icehouse we should be able (and have) to migrate to ML2.
I am testing in our dev environment with ML2 enabled.

> - Do you have flat, vlan, gre and/or vxlan networks?

> How about migrating your instances to a new compute node running
> linuxbridge agent instead? Will it update ml2_port_bindings accordingly?
Good question :) I will have a look.

I'd rather do some magic on a running or stopped machine then migrating all our instances:

We do not have shared storage and machines are paused during the whole migration process. 
This can take quite some time :( we run qemu from the redhat 6 stack and that does not do the smart snapshotting)
Another issue would be that live migration without shared storage requires you to have the original base image / snapshot available.
Especially for machines started from snapshots this is going to be an issue.
So even if this works we probably still have other issues getting there..

>> * nova - instance_info_caches - This looks like it is going to be a problem, the whole network stuff is in here.
>> Although it is called cache it does not seem to be updated if you delete the content :(
> My only real contribution to your question and sanity is this one:
>NEVER truncate that table.
Did that in our dev environment, also noticed that was not productive ;)

> And yes, it looks like Nova rebuild this table content from time to time
> using the *existing* content: it won't rebuild it from scratch if truncated.
Yes noticed that :(


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