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Configure a Replica Set for MongoDB
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Rocket.Chat uses the MongoDB replica set to improve performance via Meteor Oplog tailing. Replica sets are used to provide high data availability by maintaining multiple copies of the data across different servers.
Check the release notes to ensure you are using a compatible version of MongoDB.
To configure the replica set, add this section to the mongod.conf
file:
replication: // indicates the beginning of the replication configuration section
replSetName: "rs01"
For example, run the following command to update the replication settings in the MongoDB configuration file:
echo -e "replication:\n replSetName: \"rs01\"" | sudo tee -a /etc/mongod.conf
Restart MongoDB and initiate the replica set
Follow these steps to initiate the MongoDB replica set:
Restart MongoDB service:
sudo systemctl restart mongod
Start the MongoDB shell and initiate the replica set:
mongo > rs.initiate()
The output of the command should look like this:
{ "info2" : "no configuration specified. Using a default configuration for the set", "me" : "127.0.0.1:27017", "ok" : 1, "operationTime" : Timestamp(1538772048, 1), "$clusterTime" : { "clusterTime" : Timestamp(1538772048, 1), "signature" : { "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),"keyId" : NumberLong(0) } } } rs01:SECONDARY>
Note that the
ok
value should be1
. Any other value, i.e. 93, means something is wrong.Hit enter, you should see your prompt turn into
rs01:PRIMARY>
, this indicates the replica set is being used. Typeexit
to get back to your regular shell:rs01:PRIMARY> exit bye
Troubleshooting
Depending on your network settings, including /etc/hosts
and DNS, if you have configured Rocket.Chat to use localhost:27017
, you may see an error similar to this:
[conn1] created this configuration for initiation : { _id: "rs0", version: 1, members: [ { _id: 0, host: "test:27017" } ] }
rs.initiate()
may be defaulting to the host name e.g., test
.
You can force a different hostname as follows:
rs.initiate({ _id: 'rs01', members: [ { _id: 0, host: 'localhost:27017' } ]})
You should get a response similar to the following:
> rs.initiate({ _id: 'rs01', members: [ { _id: 0, host: 'localhost:27017' } ]})
{ "ok" : 1 }
rs0:OTHER>
Reconfigure and restart Rocket.Chat service
After you configured the replica set, you must add the MONGO_OPLOG_URL
environment variable to the service definition and restart Rocket.Chat server.
In CentOS, open the file
/usr/lib/systemd/system/rocketchat.service
In Ubuntu or Debian, open the file
/lib/systemd/system/rocketchat.service
Add the following to the environment line:
MONGO_OPLOG_URL=mongodb://localhost:27017/local?replSet=rs01
Reload the system state and restart Rocket.Chat:
sudo systemctl daemon-reload && sudo systemctl restart rocketchat