Recently, we got a couple of questions in the mailing list about running a RavenDB 4.x cluster with just two nodes in it. This was a fairly common topology in RavenDB 3.x days because each of the nodes was mostly independent, but that added a lot of operational complexity to the system. In RavenDB 3.x you had to do a lot of stuff on each of the nodes in the system. RavenDB 4.x has brought us a unified cluster management and greatly simplified a lot of operational tasks. But one of the results of this change is that we now have a cluster rather than just a bunch of nodes.
In particular, in order to be able to operate correctly, a RavenDB cluster needs a majority of the voting nodes to operate successfully. In a typical cluster setup, you are going to have three to five nodes and you’ll need two or three of them to be accessible for the cluster to be healthy.