[Linux-cluster] 2-node tie-breaking

[gordan at bobich.net]

Hi,

I've got a slightly peculiar problem. 2-node cluster acting as a load 
balanced fail-over router. 3 NICs: public, private, cluster.
Cluster NICs are connected with a cross-over cable, the other two are on 
switches. The cluster NIC is only used for DRBD/GFS/DLM and associated 
things.

The failure mode that I'm trying to account for is the one of the cluster 
NIC failing on one machine. On the public and privace networks, both 
machines can still see everything (including each other). That means that 
a tie-breaker based on other visible things will not work.

So, which machine gets fenced in the case of the cluster NIC failure (or 
more likely, if the x-over cable falls out)?

Is there a sane, tested way to handle this condition? It would be quite 
embarrasing if both, otherwise fully functional nodes, decided to shut 
fence the other one off by shutting it down.

Thanks.

Gordan