I am designing a MongoDB sharded cluster in AWS. Now MongoDB recommends C4,M4 or D2 instance types with provisioned IOPS ebs volumes to be used with MongoDB. Initially, I chose to use two configuration server replica set with 2 sharded clusters. Each sharded cluster contains 20 Gb of primary and secondary replica set. And the two application servers with MongoDB will run behind a load balancer.
My question is can I use the general purpose instance types like t3 as the application server (which will run MongoDB) or the configuration servers? Will it create performance issues? As I understand the load in the configuration server will be relatively low.