- Replication >
- Replica Set High Availability
Replica Set High Availability¶
Changed in version 3.2: MongoDB introduces a version 1 of the replication protocol (protocolVersion: 1) to reduce replica set failover time and accelerates the detection of multiple simultaneous primaries. New replica sets will, by default, use protocolVersion: 1. Previous versions of MongoDB use version 0 of the protocol.
Replica set members keep the same data set but are otherwise independent. If the primary becomes unavailable, an eligible secondary holds an election to elect itself as a new primary. In some situations, the failover process may undertake a rollback. 
|||Replica sets remove “rollback” data when needed without intervention. Administrators must apply or discard rollback data manually.|