Does my application is ready for the public Cloud ?
Before going any further, let’s give some definition about the difference between Scaling-up and Scaling-out:
Scale-up is to increase the server’s ressources (addition of RAM or CPU). This usually happen to large application which have tight coupling with the system, the only way to handle more traffic is then to add more server’s ressources.
Scale-out is to increase the number of servers in order to respond to the increased load of an application. This implies that the application has been developed in terms of distribution, that it can be executed in parallel on several servers. This is usually for API centric, SOA and micro-services.