---
title: "Configure MongoDB Replica Set for Rocket Chat"
slug: "configure-a-replica-set-for-mongodb"
description: "Set up a MongoDB replica set for Rocket Chat deployments. Ensure secure messaging, high availability, reliability, and scalable open source collaboration."
updated: 2026-01-22T14:26:59Z
published: 2026-01-22T14:26:59Z
canonical: "docs.rocket.chat/configure-a-replica-set-for-mongodb"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.rocket.chat/llms.txt
> Use this file to discover all available pages before exploring further.

# Configure a Replica Set for MongoDB

Rocket.Chat uses the [MongoDB replica set](http://docs.mongodb.org/manual/replication/) 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.

> [!NOTE]
> 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:

```bash
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:

```bash
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:

1. Restart MongoDB service:

```bash
sudo systemctl restart mongod
```
2. Start the MongoDB shell and initiate the replica set:

```bash
mongo
> rs.initiate()
```

The output of the command should look like this:

```bash
{
    "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 be `1`. Any other value, i.e. 93, means something is wrong.
3. Hit enter, you should see your prompt turn into `rs01:PRIMARY>`, this indicates the replica set is being used. Type `exit` to get back to your regular shell:

```bash
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:

```bash
[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:

```bash
rs.initiate({ _id: 'rs01', members: [ { _id: 0, host: 'localhost:27017' } ]})
```

You should get a response similar to the following:

```bash
> rs.initiate({ _id: 'rs01', members: [ { _id: 0, host: 'localhost:27017' } ]})
{ "ok" : 1 }
rs0:OTHER>
```

## Reconfigure and restart Rocket.Chat service

After you have configured the replica set, reload the system state and restart Rocket.Chat:

```bash
sudo systemctl daemon-reload && sudo systemctl restart rocketchat
```