MongoDB 3.2.x Replica Sets on AWS EC2
A MongoDB replica set provides a mechanism to allow for a reliable database services. The basic replica set consists of three servers, a primary, a secondary and an arbitrator. The primary and secondary both hold a copy of the data. The arbitrator is normally a low spec server which just monitors the other servers and help with the failover process. In production, there can be more than three servers.
To setup mongo as a replica set on Amazon Web Services EC2 you need to first setup a security group with ssh on port 22 and mongodb on port 27017. You then need to create three servers. Select Ubuntu 14.04 LTS x64 and a micro (or bigger depending on your database size, ideally you should have enough memory to match your database size) instance for the primary and secondary and a nano instance for the arbitrator.
Adjust the File System on each Server
The operating system by default will update the last access time on a file. In a high data throughput database application