Step 1. Start YB-Masters
When creating a YugabyteDB universe, the first step is to bring up sufficient YB-Masters (as many as the replication factor) with each being told about the others. These YB-Masters initialize themselves with a unique UUID, learn about each other and perform a leader election. At the end of this step, one of the masters establishes itself as the leader.
Step 2. Start YB-TServers
The next step is to start as many YB-TServers as there are nodes, with the master addresses being passed to them on startup. They start heart-beating to the masters, communicating the fact that they are alive. The heartbeats also communicate the tablets the YB-TServers are currently hosting and their load, but no tablets would exist in the system yet.
Let us illustrate this with our usual example of creating a 4-node YugabyteDB universe with a replication factor of 3. First the three masters are started in create mode. This is done explicitly to prevent accidental errors in creating a universe while it is already running.
The next step, the masters learn about each other and elect one leader.
The YB-TServers are then started, and they all heartbeat to the YB-Master.