Initializing a new replica set

In this recipe, we will be setting up the first node of a three node replica set on a single server. In a production setup, this should be on three physically separate servers.

Getting ready

By now, I am assuming you are familiar with installing MongoDB and have it ready. Additionally, we will create individual directories for each MongoDB instance:

mkdir -p /data/server{1,2,3}/{conf,logs,db}

This should create three parent directories: /data/server1, /data/server2, and /data/server3, each containing subdirectories named conf, logs, and db. We will be using this directory format throughout the chapter.

How to do it...

1. Start the first node in the replica set:

mongod --dbpath /data/server1/db --replSet MyReplicaSet

2. Open a new Terminal window, connect to the replica set node using the MongoDB shell, and check the replica set's status:

rs.status()
{
  "info" : "run rs.initiate(...) if not yet done for the set",
  "ok" : 0,
  "errmsg" : "no replset config has been received...