A sharded cluster instance consists of three components: mongos, shard, and config server. You can choose the configuration and number of mongos and shards to create ApsaraDB for MongoDB sharded cluster instances that have different performance.

Architecture

Architecture of an ApsaraDB for MongoDB sharded cluster instance

Components

Component Architecture Description
Mongos Standalone architecture

Routes queries and writes to the corresponding shards of sharded cluster instances.

You can purchase multiple mongos in the console to achieve load balancing and failover. A single sharded cluster instance supports 2 to 32 mongos.

Shard Replica set architecture (three nodes)

Stores database data.

You can purchase multiple shards in the console to scale out the capacity of data storage and concurrent read/write operations. A single sharded cluster instance supports 2 to 32 shards.

Config server Replica set architecture (three nodes)

Stores the metadata for clusters and shards. The metadata contains the data distribution information about each shard in a cluster.

Note You cannot change the specifications of the config server (one core, 2 GB memory, and 20 GB disk storage capacity).