[lvs-users] LVS + Xen issue

Matthias Saou thias at spam.spam.spam.spam.spam.spam.spam.egg.and.spam.freshrpms.net
Wed Aug 8 14:47:06 BST 2007


Joseph Mack NA3T wrote :

> On Wed, 8 Aug 2007, Matthias Saou wrote:
> 
> > I can't set up localnode, as the director and the real server are two
> > separate "logical" servers, no loopback possible.
> 
> I guess I should have seen that.
> 
> > Tips to try and debug this setup would be very welcome too ;-)
> 
> There were a bunch of people talking about LVS on virualised 
> machines in Jul.
> 
> http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.virtualised_realservers.html
> 
> you might contact them to see if any of them were running 
> the director out of the virtualised machine.

Oh, I hadn't seen that page. Unfortunately, not many implementation
details, and the focus seems to have been on OpenVZ/Vserver, which is
quite different than a Paravirtualized Xen.

I'm still troubleshooting the problem. Now I'm back from exactly 16k to
exactly 12k of data before the connection stops, and saw a bit more of
what happens : The real server and the director continue answering, but
the client sees all further packets as a different tcp connection. For
instance, my local stateful firewall drops and logs all of those
further packets.

I don't know if I'll be able to figure out why. It does seem like a
connection tracking problem somewhere on the Xen Host (dom0), or maybe
the Xen guests (domU), but I doubt it.

BTW, reproducing the problem seem pretty easy if anyone wants to also
enjoy the fun of debugging the issue :-) All it takes is a working Xen
setup on a machine with 2 NICs.

Matthias

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