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If you want to decrease the number of nodes, what happens depends on your chose COE. If you're running k8s, magnum will try to find a node with no running containers and delete them. If no empty nodes are found, magnum will warn you, and delete a node at random. With docker swarm, magnum have no logic to discover an empty node, and will just delete nodes at random.
Troubleshooting
What have been working
- Check cluster for what is wrong, usually quota
- Scale down with resize
- Fix quota
- Scale up
Debugging an uhealthy cluster
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