mongodb replication

MongoDB replication is the process of synchronizing data across multiple MongoDB servers to provide redundancy and increase data availability. Replication involves creating multiple copies of the same data on multiple MongoDB servers, called replica sets. Each replica set consists of multiple MongoDB servers, with one server acting as the primary server and the others acting as secondary servers.

In a replica set, the primary server receives all write operations and then replicates the changes to the secondary servers. The secondary servers are used for read operations and can be promoted to primary servers in the event of a primary server failure.

To set up replication in MongoDB, you need to create a replica set by configuring a group of MongoDB servers. The replica set should have at least three servers to ensure high availability, but it can have up to 50 servers. Here are the steps to create a replica set in MongoDB:

1. Start multiple instances of MongoDB servers on different machines or on the same machine with different ports.
2. Connect to one of the instances and initialize the replica set by running the rs.initiate() method.
3. Add the other instances to the replica set by running the rs.add() method.
4. Verify the status of the replica set by running the rs.status() method.

Once you have set up the replica set, MongoDB will automatically handle failover and promote a secondary server to a primary server in the event of a failure. You can also configure the replica set to provide read scaling by directing read operations to secondary servers.

In addition to providing high availability and read scaling, replication can also be used to perform backups and migrations. By replicating data to another server, you can create a backup of your data that can be used in the event of a disaster. You can also use replication to migrate data to a new server by adding the new server to the replica set and then removing the old server.