On Mon, Nov 15, 2021 at 1:18 PM Klaus Wenninger <kwenn...@redhat.com> wrote: > > > > On Mon, Nov 15, 2021 at 10:37 AM S Rogers <sa.rogers1...@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
The problem here is that nothing really triggers fencing. What happens, is - two postgres lose connection over external network, but cluster nodes retain connectivity over another network - postgres RA compares "latest timestamp" when selecting the best node to fail over to - primary postgres has better timestamp, so RA simply does not consider secondary as suitable for (atomatic) failover The only solution here - as long as fencing node on external connectivity loss is acceptable - is modifying ethmonitor RA to fail monitor operation in this case. > 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 > _______________________________________________ >> >> Manage your subscription: >> https://lists.clusterlabs.org/mailman/listinfo/users >> >> ClusterLabs home: https://www.clusterlabs.org/ >> > _______________________________________________ > Manage your subscription: > https://lists.clusterlabs.org/mailman/listinfo/users > > ClusterLabs home: https://www.clusterlabs.org/ _______________________________________________ Manage your subscription: https://lists.clusterlabs.org/mailman/listinfo/users ClusterLabs home: https://www.clusterlabs.org/