Game Server Hosting aims to match the number of available game servers to the target buffer. It’s only possible to scale the number of servers in groups equal to the server density.
The server density is defined by the worst-case usage settings of all the build configurations within the fleet, and it determines how many servers can fit per machine. The usage settings and scaling settings together determine how a fleet scales.
For example, let’s say the usage settings allow three servers per machine, and the scaling settings define a minimum of one server and a maximum of four servers within a region. The scaling system will spin up two machines because one can't run the four available servers, resulting in an available server count of six instead of four.
Game Server Hosting creates these additional servers to make the most of the available machine resources. They offer a quick way of increasing server availability without starting a new machine. By default, all servers exceeding the target maximum available scaling setting are in a stopped state until the availability buffer requires them.