[Lustre-discuss] Preferred network for OST data transfer

[Peter Grandi]

> I've just been tuning a small Lustre installation, with two
> Ethernet physical networks and have noticed that the bulk of
> the network traffic is not going through the intended network.
> The two networks are labelled tcp0 and tcp1, and tcp1 is in
> principle the best network for OST traffic, because of hardware
> and other traffic on tcp0. [ ... ] So I guess there are two
> questions - the general one of what is happening and the
> specific one of is there another parameter than can be set to
> tell the OSC which network to use?

The answer to both comes from considering this trick question:
how are LNET IP packets exempted from kernel IP routing?