How to create a MongoDB sharded cluster?

To create a MongoDB sharded cluster, follow these steps:

1. Prepare the Infrastructure:

   • Set up multiple servers or VMs for the components: shard servers, config servers, and mongos routers.
   • Ensure network connectivity between them.

2. Deploy Config Servers (Replica Set):

   • Config servers store metadata for the cluster. Deploy them as a replica set (recommended 3 nodes).
   • Example: Start 3 config servers on ports 27019, 27020, 27021:

     mongod --configsvr --replSet configReplSet --dbpath /data/configdb1 --port 27019
     mongod --configsvr --replSet configReplSet --dbpath /data/configdb2 --port 27020
     mongod --configsvr --replSet configReplSet --dbpath /data/configdb3 --port 27021
     

   • Initialize the replica set:

     rs.initiate({
       _id: "configReplSet",
       configsvr: true,
       members: [
         { _id: 0, host: "host1:27019" },
         { _id: 1, host: "host2:27020" },
         { _id: 2, host: "host3:27021" }
       ]
     })
     

3. Deploy Shard Servers (Replica Sets):

   • Each shard should be a replica set (minimum 3 nodes per shard for high availability).
   • Example: Start a shard replica set on ports 27018, 27017, 27016:

     mongod --shardsvr --replSet shardReplSet --dbpath /data/shard1 --port 27018
     mongod --shardsvr --replSet shardReplSet --dbpath /data/shard2 --port 27017
     mongod --shardsvr --replSet shardReplSet --dbpath /data/shard3 --port 27016
     

   • Initialize the replica set:

     rs.initiate({
       _id: "shardReplSet",
       members: [
         { _id: 0, host: "host4:27018" },
         { _id: 1, host: "host5:27017" },
         { _id: 2, host: "host6:27016" }
       ]
     })
     

4. Start mongos Routers:

   • mongos acts as the query router. Deploy at least one (multiple for redundancy).
   • Example: Start mongos on port 27017:

     mongos --configdb configReplSet/host1:27019,host2:27020,host3:27021 --port 27017
     

5. Add Shards to the Cluster:

   • Connect to a mongos instance and add shards:

     sh.addShard("shardReplSet/host4:27018,host5:27017,host6:27016")
     

6. Enable Sharding for a Database and Collection:

   • Enable sharding on a database:

     sh.enableSharding("myDatabase")
     

   • Choose a shard key and shard the collection:

     sh.shardCollection("myDatabase.myCollection", { "shardKeyField": 1 })
     

For production, use Tencent Cloud Database for MongoDB to simplify deployment, scaling, and management. It provides automated sharding, backups, and high availability.