what if mongos server goes down in shard cluster setup
what if mongos server goes down in shard cluster setup


As per MongoDB documentation here mongos for “MongoDB Shard,” is a routing service for MongoDB shard configurations that processes queries from the application layer, and determines the location of this data in the sharded cluster, in order to complete these operations. From the perspective of the application, a mongos instance behaves identically to any other MongoDB instance.


  My question is what happens when mongos server (foreign-connector)
  goes down.


if mongos server will goes down then config servers connection will be lost with mongos server. Then each shard in cluster connection will be lost.

As per MongoDB documentation here Enable sharding for a database to proceed, you must be connected to a mongos associated to the target sharded cluster.

For your further ref here