Cluster

A cluster consists of a config node, and multiple mongos and shard nodes.

Data read and write requests are forwarded by the mongos nodes, which read configuration settings from config, and then allocate the read and write requests to the shards, making it easy to cope with high concurrency scenarios. In addition, each config node, along with the shards in its cluster, is replicated in triplicate to ensure high availability.

Figure 1 Cluster architecture

• Each mongos is a single node, but you can provision multiple mongos nodes for load balancing and failovers. A single cluster can contain 2 to 16 mongos nodes.
• Each shard is a three-node replica set. A single cluster supports 2 to 16 shards.
• A config node is a necessary part of a cluster instance, and is also deployed as a replica set. The config node stores instance configuration data.
• Cluster is suitable for handling large amounts of data and can meet the requirements for high availability and scalability.