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Replica Set Tutorials

The administration of replica sets includes the initial deployment of the set, adding and removing members to a set, and configuring the operational parameters and properties of the set. Administrators generally need not intervene in failover or replication processes as MongoDB automates these functions. In the exceptional situations that require manual interventions, the tutorials in these sections describe processes such as resyncing a member. The tutorials in this section form the basis for all replica set administration.

Replica Set Deployment Tutorials

Instructions for deploying replica sets, as well as adding and removing members from an existing replica set.

Deploy a Replica Set
Configure a three-member replica set for either a production system.
Convert a Standalone to a Replica Set
Convert an existing standalone mongod instance into a three-member replica set.
Add Members to a Replica Set
Add a new member to an existing replica set.
Remove Members from Replica Set
Remove a member from a replica set.
Member Configuration Tutorials

Tutorials that describe the process for configuring replica set members.

Adjust Priority for Replica Set Member
Change the precedence given to a replica set members in an election for primary.
Prevent Secondary from Becoming Primary
Make a secondary member ineligible for election as primary.
Configure a Hidden Replica Set Member
Configure a secondary member to be invisible to applications in order to support significantly different usage, such as a dedicated backups.
Replica Set Maintenance Tutorials

Procedures and tasks for common operations on active replica set deployments.

Resync a Member of a Replica Set
Sync the data on a member. Either perform initial sync on a new member or resync the data on an existing member that has fallen too far behind to catch up by way of normal replication.
Change the Size of the Oplog
Increase the size of the oplog which logs operations. In most cases, the default oplog size is sufficient.
Force a Member to Become Primary
Force a replica set member to become primary.
Change Hostnames in a Replica Set
Update the replica set configuration to reflect changes in members’ hostnames.
Troubleshoot Replica Sets
Describes common issues and operational challenges for replica sets. For additional diagnostic information, see FAQ: MongoDB Diagnostics.