Command summary:
- rs.initiate( { _id: "<replicaSetName>", members: [ { _id: N, host: "<host>" } ] )
- rs.add( "<hostname>" | { host: "<hostname>" } )
- rs.remove( "<hostname>")
- rs.conf()
- rs.status()
The purpose of replication is to provide immediate online redundancy so that there is no loss of service in case of failure. Before we get into the mechanics of how to create and use replicas, it's important to gain an understanding of what MongoDB replication is and how it operates.