In horizontal scaling, we dig deep into modules that show a higher impact on the overall performance for factors such as high concurrency; so this will enable our application to serve our increased user base, which is now reaching the million mark. We also implement load balancing to process a greater amount of work. The option of adding more servers to the cluster does not require downtime, which is a definite advantage. It differs from case to case and it needs to be seen whether all the additional cost of power, licenses, and cooling is worthwhile and up to what point.
Scaling will be covered in detail in Chapter 8, Scaling.
