A replica set is a group of MongoDB instances that have the same dataset. A replica set has one arbiter node and multiple data-bearing nodes. In data-bearing nodes, one node is considered the primary node while the other nodes are considered the secondary nodes.
All write operations happen at the primary node. Once a write occurs at the primary node, the data is replicated across the secondary nodes internally to make copies of the data available to all nodes and to avoid data inconsistency.
If a primary node is not available for the operation, secondary nodes use election algorithms to select one of their nodes as a primary node.
A special node, called an arbiter node, is added in the replica set. This arbiter node ...
