In preproduction environments, it may be overkill to use the full set of servers. For efficiency reasons, we may opt to use a more simplified architecture.
The simplest possible configuration that we can deploy for sharding is the following:
- One mongos router
- One sharded replica set with one MongoDB server and two arbiters
- One replica set of config servers with one MongoDB server and two arbiters
This should be strictly used for development and testing as this architecture defies most of the advantages that a replica set provides, such as high availability, scalability, and replication of data.
Staging is strongly recommended to mirror our production environment in terms of its servers, configuration, and (if possible) dataset requirements too, in order to avoid surprises at deployment time.