The obvious reason to set up a cluster is that sometimes, a single server is not enough to serve the whole world. Scaling is needed. Setting several servers in several regions of the world could solve this, but separate servers imply other tasks such as reference data replication and sharing users. A cluster is the solution to these business needs. There are three main advantages to setting up a cluster:
- High throughput
- Data redundancy
- High availability (HA)
If you are working on a business project and you want 24/7 availability, you need a cluster.