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# CDC setup in Mongo

## CDC Setup on Linux

1\. Need to set the following in **mongod.conf** configuration file.

```

replSetName: “replica_name”
opLogSizeMB: <integer>
replSetName - You can give any name. Use command rs.status() to get this replica set name.
opLogSizeMB - When you start a replica set member for the first time, MongoDB creates an oplog with a default size. Default size is 5% of physical memory.
Lower bound is 50MB and the upper bound is 50GB. To set this please refer to this 
blog
.
```

* Set the replication name and oplog size
* replSetName: "replica\_name"
* opLogSizeMB: \<integer>
* replSetName - You can give any name. Use command rs.status() to get this replica set name.
* opLogSizeMB - When you start a replica set member for the first time, MongoDB creates an oplog with a default size. Default size is 5% of physical memory.
* Lower bound is 50MB and the upper bound is 50GB. To set this please refer to this [blog](https://docs.mongodb.com/v4.0/core/replica-set-oplog/#oplog-size).

2\. After setting up the above parameters restart the mongoDB.

```
sudo service mongod restart
```

Check the status

```
sudo service mongod status
```

3\. Now initiate the replica set run query

```
rs.initiate({_id: "replica_name", members: [{_id: 0, host: "<host_address>:27017"}]})
```

‍This will return { "ok" : 1 }