[openstack-dev] [networking-ovn] ovn-northd is a spof

Russell Bryant rbryant at redhat.com
Wed Nov 11 01:21:59 UTC 2015


On 11/10/2015 07:06 PM, gong_ys2004 wrote:
> Regard this, I read some architecture doc of it, SPOF in OVN way exists
> in two place:
> 1. ovn-northd, I don't know if we can run multiple ones, but the arch
> doc demos only one

The idea is that we will make it so you can run multiple.  We haven't
done it yet, though.  In the meantime, the expectation is that you can
easily run it in active/passive HA mode.  That will impact scale,
though.  A single ovn-northd is obviously not the longer term goal.

> 2. north db and south db, currently it is a OVSDB respectively, I don't
> think the distributed db layer can be easily and quickly solved.

Someone is actually already looking at distributing ovsdb-server.  If
that doesn't work out, the project has been pretty clear from the
beginning that the use of ovsdb-server was for convenience and if it
doesn't work, we'll switch.

I've been planning to write a FAQ in the networking-ovn documentation.
Some comments about our plans around HA are part of it.  I'll try to get
that written this week.

> curiously, why we adopt two dbs design at the beginning. why does not
> the ovn neutron plugin interact with south db?

We could write directly to the southbound db and cut ovn-northd and the
northbound db off, but we'd have to implement all of the logic from
ovn-northd in Neutron in that case.  The northbound db is a much simpler
model.

-- 
Russell Bryant



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