Your system is successfully deployed in produciton, but is still running on a single server. Not only it will soon reach its hardware capacity, it is at constant availability risk. The system is based on actor model, and one of the reasons for the choice was built-in scalability: frameworks like Akka let you seamlessly distribute the load between multiple cluster nodes, and actors have location transparency. Is this what you need? When is it right time to support clustering? And what are the main patterns of the cluster solution?
We had to answer these questions in our project at Norwegian Broadcasting Corporation (NRK) extending our system with cluster support. Some of the lessons we learned apply not only to the actor model but to general problems of scalability and domain-driven design. We will share with you our experience and run a small cluster right from a Visual Studio Code terminal window.