This tutorial will guide you through the process of setting up MongoDB replication and sharding. Replication ensures data availability and fault tolerance, while sharding allows for horizontal scaling of your MongoDB database.

Replication

Replication in MongoDB involves creating copies of data across multiple servers. This is done to ensure that data is available even if one of the servers fails.

Replication Process

  1. Primary Node: The primary node is the master copy of the data. All write operations are performed on the primary node.
  2. Secondary Nodes: Secondary nodes store copies of the data. They can accept read operations and can become the primary node if the primary fails.
  3. Arbiter Nodes: Optional nodes that help maintain the replication process but do not store data.

Setting Up Replication

To set up replication, follow these steps:

  1. Start the MongoDB server on the primary node.
  2. Start the MongoDB server on the secondary nodes with the --arbiter flag.
  3. Connect to the primary node using the MongoDB shell and add the secondary nodes to the replica set.
rs.initiate({
  _id: "myReplicaSet",
  members: [
    { _id: 0, host: "localhost:27017" },
    { _id: 1, host: "localhost:27018" },
    { _id: 2, host: "localhost:27019", arbiterOnly: true }
  ]
});

Sharding

Sharding allows for horizontal scaling of your MongoDB database. It divides the data into smaller chunks called "chunks" and distributes them across multiple servers.

Sharding Process

  1. Shard: A shard is a process that stores a portion of the data.
  2. Config Server: The config server stores metadata about the sharded cluster, such as the location of each chunk.
  3. Mongos: The Mongos process is responsible for routing read and write operations to the appropriate shard.

Setting Up Sharding

To set up sharding, follow these steps:

  1. Start the MongoDB server on the config server.
  2. Start the MongoDB server on the shards.
  3. Start the MongoDB server on the Mongos router.
  4. Connect to the Mongos router and enable sharding.
sh.enableSharding("myDatabase")
sh.shardCollection("myDatabase.myCollection", { "keyField": 1 })

Resources

For more information on MongoDB replication and sharding, please refer to the following resources:

Replication Architecture