Shared Storage (Ceph)

While Docker Swarm is great for keeping containers running (and restarting those that fail), it does nothing for persistent storage. This means if you actually want your containers to keep any data persistent across restarts (hint: you do!), you need to provide shared storage to every docker node.

This is a companion discussion topic for the original entry at

Thank you for the great guide!

Is this configuration expandable? Is it possible to add nodes and change redundancy configuration on the live cluster?

And what was the problem with GlusterFS? There’s an anchor to explanation, but it doesn’t exist. Perhaps, something has changed since 2019?

Sort of. Ceph is happy to extend storage space by adding OSD, but changing the redundancy configuration is usually not as easy. You could (for example) change your failure domain from host to rack, for example, but once you’ve created a pool of 3 replicas, you’re stuck with it. Any other configuration will require a new pool, and a long and painful (ask me how I know!) migration…

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