Replication In MongoDB

Replication In MongoDB

♦ Replication is the process of creating and maintaining the multiple copies of data across the different servers and also ensuring the copy of the data remains consistent and updated.

♦ Replica set is one of the ways of implementing the replication in MongoDB.

♦ Replica set is a specific implementation configuration of replication in MongoDB.

 

Replica Set:

♦ It is a group of MongoDB instances that work together to maintain the same data It consists of multiple servers.

♦ The minimum recommended configuration for a replica set is three members which includes one primary and two secondary nodes.

♦ A replica set can have maximum up to 50 members but only seven voting members which are used to help in electing the primary node.

♦ A replica set can have up to 50 Members but only 7 voting members.

 

Advantages of using Replication:

1. Data Redundancy

2. High Availability

3. Scalability

4. Load Balancing

5. Fault Tolerance

6. Disaster Recovery

 

Members of replica set:

1. Primary node

2. Secondary node

3. Arbiter node

4. Oplogs

 

1. Primary node :

♦ It is the primary source of data modifications, which handles all the write operations and applies all the write operations to the dataset.

♦ It keeps tracking of the replica set’s Oplog.

♦ It handles both the read and write operations from the client’s application.

♦ Secondary nodes will replicate the Oplog which is generated from the write operations from the primary node.

♦ It ensures the health and data consistency within the replica set.

 

2. Secondary node:

♦ These nodes will replicate the primary node Oplog and also it acts as backup, ensuring that these nodes are always up to date with the data in the primary node.

♦ Replica set can have more than two secondary nodes.

♦ Secondary nodes are used to read the data.

♦ If the primary node fails, one of the secondary nodes will be elected as the new primary node.

♦ Secondary nodes should be monitored regularly to ensure their health and performance.

 

3. Arbiter node:

♦ The arbiter node will not store any replica sets in it.

♦ Main use of the arbiter node is to participate in the election when the primary fails to work which helps in the situation of tie in the election process.

♦ It helps in maintaining the replica set’s fault tolerance.

♦ This does not affect the storage capacity of the replica set.

 

4. Oplog:

♦ It is expanded as an operation log.

♦ It is a capped collection which is present in the primary node.

♦ Oplog is used for secondary nodes to replicate the data from the primary node in an asynchronous process.

♦ The default size of Oplog is 50MB, you can increase the size of the Oplog based on your application requirements up to 50gb.

 

Author    : Teja

LinkedIn : https://www.linkedin.com/in/teja-sai-nadh-reddy-tatireddy-048882201

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