[Linux-cluster] 2-node tie-breaking

[Brian Kroth]

A simple way might be to check for that case specifically and assign a
preference to the node you want to win.  For instance:

if $can_ping_internal_nodes \
	&& $can_ping_external_nodes \
	&& ! $can_ping_cluster_node; then

	if [ $HOSTNAME == node2 ]; then
		self_fence
	else
		steal_cluster_nodes_resources
	fi
fi

I know that you can do this via clever scoring in heartbeat [1], but I'm
not sure about rgmanager.

[1] linux-ha.org

Brian

gordan at bobich.net <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
>
> --
> Linux-cluster mailing list
> Linux-cluster at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-cluster
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/x-pkcs7-signature
Size: 2192 bytes
Desc: not available
URL: <http://listman.redhat.com/archives/linux-cluster/attachments/20080207/aa9fc3a9/attachment.bin>