Deploy a Replica Set¶
To deploy a replica set with enabled access control, see Deploy New Replica Set with Access Control. If you wish to deploy a replica set from a single MongoDB instance, see Convert a Standalone to a Replica Set. For more information on replica set deployments, see the Replication and Replica Set Deployment Architectures documentation.
Three member replica sets provide enough redundancy to survive most network partitions and other system failures. These sets also have sufficient capacity for many distributed read operations. Replica sets should always have an odd number of members. This ensures that elections will proceed smoothly. For more about designing replica sets, see the Replication overview.
For production deployments, you should maintain as much separation between
members as possible by hosting the
instances on separate machines. When using virtual machines for
production deployments, you should place each
instance on a separate host server serviced by redundant power circuits
and redundant network paths.
Before creating your replica set, you should verify that your network configuration allows communication among all members; i.e. each member must be able to connect to every other member. For instructions on how to check your connection, see Test Connections Between all Members.
Considerations When Deploying a Replica Set¶
In a production, deploy each member of the replica set to its own machine
and if possible bind to the standard MongoDB port of
27017. Use the
bind_ip option to ensure that MongoDB listens for connections
from applications on configured addresses.
See Replica Set Deployment Architectures for more information.
Ensure that network traffic can pass between all members of the set and all clients in the network securely and efficiently. Consider the following:
- Establish a virtual private network. Ensure that your network topology routes all traffic between members within a single site over the local area network.
- Configure access control to prevent connections from unknown clients to the replica set.
- Configure networking and firewall rules so that incoming and outgoing packets are permitted only on the default MongoDB port and only from within your deployment.
Finally ensure that each member of a replica set is accessible by
way of resolvable DNS or hostnames. You should either configure your
DNS names appropriately or set up your systems’
/etc/hosts file to
reflect this configuration.
Specify the run time configuration on each system in a configuration
file stored in
or a related location. Create the directory where MongoDB stores data
files before deploying MongoDB.
For more information about the run time options used above and other configuration options, see Configuration File Options.
The following procedure outlines the steps to deploy a replica set when access control is disabled.
Start each member of the replica set with the appropriate options.¶
For each member, start a
mongod and specify the replica set
name through the
replSet option. Specify any other parameters
specific to your deployment. For replication-specific parameters, see
If your application connects to more than one replica set, each set should have a distinct name. Some drivers group replica set connections by replica set name.
The following example specifies the replica set name through the
--replSet command-line option:
mongod --replSet "rs0"
mongod --config $HOME/.mongodb/config
In production deployments, you can configure a init script to manage this process. Init scripts are beyond the scope of this document.