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.
Architecture
| Component type | Architecture | Description |
|---|---|---|
| Mongos | Standalone |
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. |