Mesos is proven at massive scale (Apple use it for Siri, Twitter use it for their data warehouse). You can run a cluster of 10k nodes if you want. I believe the

Mesos is proven at massive scale (Apple use it for Siri, Twitter use it for their data warehouse). You can run a cluster of 10k nodes if you want. I believe they have run simulations at higher scale than that. Docker Swarm is not yet proven at such scale. They have run perf tests at 1k nodes, which is high enough for most use cases, but not for truly warehouse-scale computing. 1k nodes is also where Kubernetes tops out at (though expect that to be higher in Kubernetes 1.3, which should be released in the coming weeks). On the other hand, if you're trying to run Docker container workloads, it's going to be easier in a Docker-first cluster orchestrator like Docker Swarm or Kubernetes; Mesos has Docker support but it's not as tightly integrated, and doesn't implement the full Docker management API.