Replicate Set Mongo

On this tutorial, I will explain how to set a Replicate for MongoDB.

Firstly, we need to stop mongo process:

mongodb stop

Then, create directories for stocking the database:

mkdir data/db1
mkdir data/db2
mkdir data/db3

Launch the mongodb instance for each directory:

mongod --port 27017 --dpath data/db1 --replSet repl
mongod --port 27018 --dpath data/db2 --replSet repl
mongod --port 27019 --dpath data/db3 --replSet repl

The replicate set is called 'repl' for this example.

The first part is done, now wee need to configure the replicate set.

Launch the mongo client (without parameters):

mongo

Into mongo client, we need to write configuration:

cfg = {_id:"repl", members : [{_id: 0, host: "localhost:27017"},{_id:1, host:"localhost:27018"},{_id:2, host:"localhost:27019"}] }

Free to you to change the url of mongoDB instance if instances are located on different servers.

We need to initiate it:

rs.initiate(cfg)

Then, you will see a success message like:

{
"info" : "Config now saved locally. Should come online in about a minute.",
"ok" : 1
}

After few seconds, you will see servers instance for checking master and slaves replicate set. On the client mongo, push the 'Enter' button, you will see the prompt changing:

rep:PRIMARY>

If this appended, that is to say your replication set is Done.