Description

In "Deploy a Geographically Redundant Replica Set", the following advice appears:

Deploy a Geographically Redundant Three-Member Replica Set

For a geographically redundant three-member replica set deployment, you must decide how to distribute your system. Some possible distributions for the three members are:

• Across Three Data Centers: One members to each site.
• Across Two Data Centers: Two members to Site A and one member to Site B. If one of the members of the replica set is an arbiter, distribute the arbiter to Site A with a data-bearing member.

While these are both valid configurations, the documentation should perhaps mention (here) that the three-site solution has several advantages over the two-shard solution, especially for CSRS config servers.

Scope (pages to review):

• https://docs.mongodb.com/manual/tutorial/deploy-geographically-distributed-replica-set/
• https://docs.mongodb.com/manual/core/replica-set-architecture-geographically-distributed/
• https://docs.mongodb.com/manual/core/replica-set-architectures/
• production notes