Deploy a Sharded Cluster

• Start the Config Server Database Instances

for example : 

mongod --configsvr --dbpath <path> --port <port>

mongod --configsvr --dbpath /data/configdb --port 27019

 

In production deployments, you must deploy exactly three config server instances, each running on different servers

to assure good uptime and data safety. In test environments, you can run all three instances on a single server.

 

• Start the mongos Instances

for example : 

mongos --configdb <config server hostnames>

mongos --configdb cfg0.example.net:27019,cfg1.example.net:27019,cfg2.example.net:27019

 

• deploy replica sets for each shard

A shard can be a standalone mongod or a replica set. In a production environment, each shard should be a replica set.

for example : 

cfg = ...

rs.initiate(cfg)

rs.conf()

rs.status()

rs.add("<hostname><:port>")

• Add Shards to the Cluster

for example : 

sh.addShard("rs1/mongodb0.example.net:27017")

 

• Enable Sharding for a Database

for example : 

sh.enableSharding("<database>")

 

• Enable Sharding for a Collection

for example : 

sh.shardCollection("<database>.<collection>", shard-key-pattern)

sh.shardCollection("events.alerts", { "_id": "hashed" } )