MongoDB Replica Set Setup — 3-Node HA Configuration

I will configure a MongoDB three-node replica set for your environment — covering primary and secondary node configuration, arbiter setup if three data nodes are not available, replica set initialisation and member addition, read preference configuration for secondary reads, write concern configuration for durability guarantees, replica set health monitoring, and a planned failover test confirming automatic primary election completes within your RTO. A MongoDB standalone instance is a single point of failure; a three-node replica set provides automatic primary failover, data redundancy across three nodes, and the ability to route read operations to secondaries to distribute read load — all from a MongoDB configuration change rather than a major infrastructure redesign.

The configuration covers rs.initiate() with all members, priority and hidden member configuration, write concern (majority) and read concern (majority) for strong consistency, read preference configuration for secondary reads in your application, replica set status monitoring with rs.status(), and an operations runbook for primary stepdown, member addition, and forced primary election.

Designed for organisations running MongoDB in production on a standalone instance without HA, or with a replica set configured without write concern and read concern settings providing the desired consistency guarantees.