If you're talking about Akka Cluster sharding, basically any situation where you have distributed objects that have their own state and behavior. I've had two p

If you're talking about Akka Cluster sharding, basically any situation where you have distributed objects that have their own state and behavior. I've had two projects where objects needed to stay in memory so they could receive messages, update their state, and then behave by sending messages to other objects. And it was too many objects to live in one server. The naive solution of data repositories and caching isn't really sufficient for this, and a horizontally scaled Akka Cluster Sharding setup with Persistence was the right solution given the requirements.