On Mon, Dec 12, 2016 at 11:26 PM, Ben Pfaff <[email protected]> wrote:

> On Fri, Nov 11, 2016 at 08:52:57PM +0530, Numan Siddique wrote:
> > With the commit - "ovsdb-server: Implement read-only remote connection
> type." merged, this patch series is the next step in making ovn-controller
> a read-only client to the Southbound DB.
> >
> > Patch 1 removes the chassis creation code from ovn-controller. It now
> expects the chassis row to be created in the Chassis table.
> > Patch 2 removes the ovn-controller setting the chassis column of Port
> binding. Instead ovn-northd will set it.
> >
> > Since ovn-controller is not setting the chassis column, one side effect
> of this patchset is the Logical_Switch_Port.up doesn't reflect the
> > true value. Is this limitation acceptable ?
>
> I have a couple of thoughts here.
>
> One is that, as we make this kind of change, we need to figure out the
> upgrade path.  Maybe, we need to write a skeleton upgrade document (I
> seem to recall that Russell has started on this), and then each change
> that is relevant for upgrade needs to update the upgrade document
> appropriately.
>
> I'm not super happy with the idea of Logical_Switch_Port.up being
> inaccurate.  For one, I understand that OpenStack wants to wait until
> networking is up for something or other.
>
>
​Does the proposal of using ovsdb locks to set the LSP "up" or "down" seems
OK to you. I was thinking of posting the code which I have for review after
testing it more  thoroughly as v2 to this series.

​


> Let me make a straw man proposal for how to solve this kind of problem.
> Suppose that we abandon the idea of making OVN 100% database-driven, by
> introducing a central RPC server.  The RPC server could be part of
> ovn-northd, or it could be a separate daemon.  In any case, it would
> provide specific access to the kinds of database writes that until now
> the HVs have done directly.  For example, it would include an RPC for
> marking an LSP "up" or "down".
>
>
Another approach which comes to my mind, is it to enhance ovsdb-server to
support in memory tables​ ? (like we can define the table to be in-memory
in the schema). Whatever the rows added/modified by the clients will be
lost when the ovsdb-server is restarted.

With this approach we could solve both the LSP up/down problem and mac
binding problem.


Such an RPC server would essentially be stateless, since it would just
> be a database client without internal state of its own, and thus it
> would work OK to run any number of copies of it without special
> synchronization or HA support.
>
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