> ## Documentation Index
> Fetch the complete documentation index at: https://docs-v2.ard.co/llms.txt
> Use this file to discover all available pages before exploring further.

# MongoDB on cluster-n03 / cluster-n04

> MongoDB deployment and replica set details on the n03/n04 databases cluster.

## MongoDB topology

MongoDB is present on both nodes of the databases cluster, but with different roles:

* `cluster-n03` – **active mongod service**, part of replica set `rs1` and typically the PRIMARY.
* `cluster-n04` – MongoDB binaries/tools are available, but there is **no active `mongod.service`** or `/etc/mongod.conf` under systemd.

## MongoDB on cluster-n03

* **Version**: `db version v3.4.13`
* **Service**: `mongod.service` (enabled, active)
* **Binary / config**:
  * Service command: `/usr/bin/mongod --config /etc/mongod.conf`
  * `dbPath: /data/mongo`
  * `port: 27017`
  * `bindIp: 0.0.0.0`
  * `replication.replSetName: rs1`

Useful commands:

```bash theme={null}
ssh cluster-n03
systemctl status mongod
mongo --quiet --eval 'rs.status().members.map(m => ({name: m.name, stateStr: m.stateStr}))'
```

MongoDB on `cluster-n03` is part of replica set **`rs1`** and is typically the **PRIMARY** node used by applications.

## MongoDB on cluster-n04

* **Version**: `db version v3.6.8` (tools installed)
* **Service**:
  * `mongod.service` is **not found** under systemd.
  * `/etc/mongod.conf` is **not present**.

Implications:

* This host may participate in the MongoDB topology in a different way (e.g. containerized `mongod`, alternate service name) or not at all.
* Do **not** assume MongoDB failover to `cluster-n04` without verifying the actual deployment.

## Operational notes

* Treat `cluster-n03` as the **main MongoDB node** for now.
* Before relying on `cluster-n04` for MongoDB HA, confirm:
  * How (or if) it joins replica set `rs1`.
  * Where its data path and configuration live.
  * How applications discover and connect to the replica set.