What-happens-when-eth2-is-down
St first, everything seems to work.
Load goes up slightly (~ to 4) when it should be at 0 (yep, I set /etc/nologin so the headnode should be really really idle).
But Munin gets clogged-up and then NFS gets really really clogged-up.
Probably IB is not very good when everything goes through it. Somewhere I heard about that.
Also:
sudo ifup eth2 Starting NFS common utilities: statd idmapd.
This could be a configuration BUG and not an IB deficiency as mentioned earlier.