[ClusterLabs] Fence node when network interface goes down

[Klaus Wenninger]

On Mon, Nov 15, 2021 at 10:37 AM S Rogers <sa.rogers1342 at gmail.com> wrote:

> I had thought about doing that, but the cluster is then dependent on the
> external system, and if that external system was to go down or become
> unreachable for any reason then it would falsely cause the cluster to
> failover or worse it could even take the cluster down completely, if the
> external system goes down and both nodes cannot ping it.
>
You wouldn't necessarily have to ban resources from nodes that can't
reach the external network. It would be enough to make them prefer
the location that has connection. So if both lose connection  one side
would still stay up.
Not to depend on something really external you might use the
router to your external network as ping target.
In case of fencing - triggered by whatever - and a potential fence-race
you might use the rather new feature priority-fencing-delay (give the node
that is running valuable resources a benefit in the race) or go for
fence_heuristics_ping (pseudo fence-resource that together with a
fencing-topology prevents the node without access to a certain IP
from fencing the other node).
https://clusterlabs.org/pacemaker/doc/deprecated/en-US/Pacemaker/2.0/html/Pacemaker_Explained/s-cluster-options.html
https://github.com/ClusterLabs/fence-agents/blob/master/agents/heuristics_ping/fence_heuristics_ping.py

Klaus
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