The DDS provides three types of instances: cluster version, replica set, and stand-alone version, each of which uses different deployment architectures to meet different business needs.
Cluster Version
A sharded cluster provides Mongos, Shard, and ConfigServer nodes. Each Shard and ConfigServer are composed of replica sets. Each replica set uses the three-node master-slave mode.
This version is applicable to highly concurrent read and write scenarios. You can freely select the number and configuration of Mongos and Shard nodes to improve performance and expand storage space, and build sharded cluster instances with different performance to meet different business requirements.
Replica Set
A replica set provides nodes of different roles, one Primary node for read and write, one, three, or five Secondary nodes for providing high availability, one Hidden node that is invisible to users.
It is applicable to small and medium-sized business systems that require high availability and a high number of reads but less writes. Secondary can be added as needed to improve the read performance.
Stand-alone Version (Single-Node)
For the stand-alone version, only one node is deployed on a VM and no advanced features, for example, high availability, are available. The advantage is high cost performance.
This version is applicable to R&D testing, learning and training, and non-enterprise core data storage scenarios.