Setting up MongoDB replica set - mongodb

Question

I have a fast Windows 7 PC with 8Gb RAM. I want to test this MongoDB replica set: http://www.mongodb.org/display/DOCS/Replica+Sets for my development. I dont want to buy 3 PCs though, as it's kind of expensive. Is there a way to use some kind of technology, like Hyper-V, to be able to set it up? If not, how many PC and what kind should I buy?

Answer 1

You can run multiple mongod processes on the same machine on different ports and pointing to different data directories and make them a part of the same replicaset.
http://www.mongodb.org/display/DOCS/Starting+and+Stopping+Mongo
mongod --dbpath c:/data1 --port 12345 --replSet foo
mongod --dbpath c:/data2 --port 12346 --replSet foo
and then connect to one of the mongod processes using the mongo console and add initiate the replica set using instructions outlined here:
http://www.mongodb.org/display/DOCS/Replica+Sets+-+Basics

Answer 2

On Ubuntu 18.04, MongoDb : shell version v4.2.6
In The Terminal (1) (Secure the port using a firewall since we are using 0.0.0.0)
sudo systemctl stop mongod
sudo systemctl status mongod
sudo mongod --auth --port 27017 --dbpath /var/lib/mongodb --replSet rs0 --bind_ip 0.0.0.0
Then open another instance of terminal (2) (Keep the previous one open)
mongo -u yourUserName -p (it will ask for password - follow on)
rs.initiate()
Then open yet another instance of terminal (3)
Here you will run server.js with your connection url like this :
const url = 'mongodb://' + user + ':' + password +
'#localhost:27017/?replicaSet=rs0'
MongoClient.connect(url, { useUnifiedTopology: true, authSource: 'admin' },
function (err, client) {
if (err) {
throw err;
}
});

Answer 3

you can create multiple mongod instances running on the same server on diff. ports.
for configuration and the way replica set works, refer to blog below. this will set up replica set as per the instruction on the same box.
http://pareshbhav.blogspot.com/2014/12/mongdb-replicaset-and-streaming.html

Answer 4

One super easy way is to set the MongoDB replica set by using Docker.
Within our Docker Host, we can create Docker Network which would give us the isolated DNS resolution across containers. Then we can start creating the MongoDB docker containers. They would initially be unaware of each other. However, we can initialise the replication by connecting to one of the containers and running the replica set initialisation command. Finally, we can deploy our application container under the same docker network.
Check out the MongoDB replica set by using Docker post on how to make this work.

Answer 5

There is no use in having replica set at the same single host since this contradicts the terms of redundancy and high availability. If your PC goes down or slows down, your replica set will be ruined or undergo degradation. But for sure it’s not cost-efficient to buy several PCs to evaluate replica set, so you can consider a possible scenario described in MongoDB Replica Set with Master-Slave Replication.
With respect to the number of replica set members, you’re right, the most common topology comprises 3 members, but I would suggest you also adding an Arbiter on the separate host. It is a lightweight process and doesn’t require a lot of resources but it plays an important role in maintaining a quorum in an election of new PRIMARY in case you got an even number of members once PRIMARY fails.

Answer 6

We will configure MongoDB replica set with 3 nodes.
Suposse we have 3 nodes with:
hostname Mongodb01, ip address 192.168.1.11 and MongoDB
installed with port no 27017
hostname Mongodb02, ip address 192.168.1.22 and MongoDB installed with port no 27017
hostname Mongodb03, ip address 192.168.1.33 and MongoDB
installed with port no 27017
Before initiating with this configuration, ensure that you have below points in place:
MongoDB service is installed and running in all the 3 nodes
All the 3 nodes are connected to each other via IP Address or Hostname
The default port nos 27017 and 28017 (or any other port no you are planning to use) are not blocked by any firewall or antivirus
Now, lets begin with configuration
Step 1: Modify the mongodb.conf file of each node to include replica set information.
replSet = myCluster
rest = true
replSet is the unique name of replica set and all the nodes must have same value for replSet parameter. rest is optional but used to enable rest interface for admin web page.
Step 2: Restart MongoDB service on all the 3 nodes
Step 3: Configure replica set on the node you plan to use as primary. In our case we will execute below commands in Mongodb01's mongo shell
rs.initiate()
Initiates replica set
rs.add("<hostname or ip-address>:<port-no>")
Adds secondary node in replica set.
e.g.; rs.add("Mongodb02:27017") or rs.add("192.168.1.22:27017")
rs.addArb("<hostname or ip-address>:<port-no>")
Adds arbiter node in replica set.
e.g.; rs.addArb("Mongodb03:27017") or rs.add("192.168.1.33:27017")
rs.status()
Checks whether all the nodes are added in the replica set. Other way of checking for the nodes in replica is use following URL in your browser address bar http://<hostname or ip-address>:<port>/_replSet
e.g.; http://localhost:27017/_replSet or http://Mongodb01:27017/_replSet or http://192.168.1.11:27017/_replSet.
This URL is accessible only when you set rest = true in mongodb.conf file