To convert a standalone server into a replica set, we first need to cleanly shut down the mongo server:
> use admin
> db.shutdownServer()
Then, we start the server with the --replSet configuration option via the command line (which we will do here), or by using a configuration file, as we will explain in the next section:
- First, we connect (via the mongo shell) to the new replica set enabled instance, as follows:
> rs.initiate()
- Now, we have the first server of our replica set. We can add the other servers (which must have also been started with --replSet) by using the mongo shell, as follows:
> rs.add("<hostname><:port>")
Double-check the replica set configuration by using rs.conf(). Verify the replica set status by using rs.status().