Atlas Dedicated Server Setup Guide - Part 1: How it works
The Atlas Cluster
Atlas is a collection of individual servers hosing individual maps. Each map represents a grid on a world map. Similar to any other MMO with zonelines, you can travel from map to map within Atlas by traveling to the edge of one map, the game transfers you to the next server, and you continue your adventure within the next area. For example, you can see that there are 6 squares in the below map create utility which represents 6 different maps to create one large game world.
Each map can support ~ 150 players (based on official Atlas servers) with some variance for the system performance that is running the server. The map acts like a globe; traveling off the edge on the left will move you to the map on the opposite far right. Same with the top and bottom.
The map servers are instances of the shootergameserver.exe. These can all run on the same computer (if you have the CPU and memory), or they can be distributed across multiple physical or virtual machines. The clusters are designed to be salable and distributed across servers or facilities, as required.
Elements of the Cluster
REDIS is the database that all the servers need to communicate with. It contains the shared configuration settings across all the maps (like players, tribes, ect) which allows members to travel from one zone to another. During login, the database tells the logon server which host has your character and sends your client traffic to the right server.
shootergameserver.exe (Atlas Server)
This is the server executable for the Atlas cluster. Each map is loaded up with this executable and a variety of command arguments that follow it. On a server with multiple instance, the executable is called multiple times and the command arguments provide the details so the servers load different maps.
Atlas does not currently support LAN connection, in v14, without using a hairpin NAT (not covered in this guide). There's a chance it will come later like ARK did when it was first released. However, I haven't seen anything confirmed yet.