A sharded cluster instance consists of three types of components: mongos, shard, and Configserver nodes. You can choose the configurations and number of mongos and shard nodes to create ApsaraDB for MongoDB sharded cluster instances that have different performance capabilities.
A mongos node routes queries and writes to the corresponding shard nodes.
You can purchase multiple mongos nodes to implement load balancing and failover. By default, a single sharded cluster instance supports up to 32 mongos nodes.
|Shard||Replica set (primary, secondary, and hidden nodes + read-only nodes)||
A shard node stores database data.
You can purchase multiple shard nodes to scale out instance storage and capability to handle concurrent read and write requests. By default, a single sharded cluster instance supports up to 32 shard nodes.
Important Read-only nodes must be purchased separately. The price of a single read-only node is the same as that of a single shard node.
|ConfigServer||Replica set (three nodes)||
A Configserver node stores the metadata of shard nodes. Shard metadata is the types of data stored in each shard node.