Initiate the Config-Server Replica Set
Initiate the config-server mongod instances (three-member replica set) that will host the configuration data of your sharded MongoDB deployment.
Before you begin
Before initiating the config server replica set, verify the following in the MongoDB
configuration file:
- Verify that the
replication
option is set toMtxEventReplSet
. - Verify that the
authorization
option is set toenabled
. - Verify that all
mongod
instances on each of the MongoDB host servers are started.
Important: Starting in MongoDB 4.0, you cannot specify the
--nojournal
option or storage.journal.enabled:
false
for replica set members that use the WiredTiger storage
engine. Refer to the MongoDB product documentation for compatibility changes in
MongoDB 4.0.About this task
The instructions in this procedure initiate a single replica set with three
mongod
instances.
Procedure
-
Connect to one of the
mongod
instances locally. -
Using the MongoDB mongo shell CLI, enter the rs.initiate()
command to initiate the config server replica set.
mongo –port 27019 rs.initiate({ "_id": "MtxConfigReplSet", configsvr: true, "members": [ {"_id": 0, "host": "ip1:27019"}, {"_id": 1, "host": "ip2:27019"}, {"_id": 2, "host": "ip3:27019"}
where:- ip1, ip2, and ip3 are the hostnames (or IP addresses) and port numbers of the host servers where mongod instances of the config servers are to run. The port number is required only if the port number is not the default (27017).
-
Identify the replica set primary (
mongod
primary) by issuing the mongo shell CLI commandrs.status()
on any server.A few seconds after the replica set is initialized, one
mongod
instance is elected as the primary of the replica set. All changes to the replica set must be done when connected to the primary from this point in the setup instructions.
What to do next
After you initiate the config-server replica set, start all mongos
instances
in your deployment in preparation for creating users for each shard replica set.