I agree there is no one-size-fits-all for data replication. Currently Uncloud doesn't handle volume replication. Moreover it doesn't support regular Docker volumes yet, only mounting a host path. The reason is I didn't have time to give it proper thought on how to design volumes in a cluster context without getting into the full-blown PV support like in K8s.

I suspect that I will implement support for regular local Docker volumes such that each service container will use its own volume on the machine it runs on. Uncloud won't automatically replicate data between volumes as storage replication adds significant complexity and potential failure modes. Apps that need HA such as databases can handle their own replication. I'm getting inspiration from Fly for this: https://fly.io/docs/volumes/overview/. Maybe it would make sense to implement handy commands for cloning, moving, and backing up volumes between machines, not sure yet.

Corrosion (the embedded CRDT SQLite) is only used for Uncloud's internal state management, not for application data.