"Scalability" is the ability of a system, network, or process to cope with an increase in workload; a property that provides a predictable increase in system characteristics: for example, the number of supported users, responsiveness, overall performance, and so on.
"Scalability" is an important aspect of electronic systems, software complexes, database systems, routers, networks, if they require the ability to work under heavy load. A system is called scalable if it is able to increase performance in proportion to additional resources. Scalability is also understood as the possibility of increasing additional resources without structural changes to the system. In a system with poor scalability, adding resources leads only to a slight increase in performance, and from a certain "threshold" moment, adding resources does not give any useful effect.
"Vertical scaling" is the ability to replace components in an existing computing system with more powerful and faster ones as requirements grow and technologies develop. This is the easiest way to scale, as it does not require any changes to the application programs running on such systems.
Horizontal scaling — the ability to add new nodes and servers to the system to increase overall performance. This method of scaling may require changes to programs so that they can take full advantage of the increased amount of resources.
The conditions of modern business are changing very quickly, which makes long-term planning impossible, requiring a comprehensive and long-term analysis of already outdated data. Instead comes a strategy of gradually increasing the power of information systems.
On the other hand, changes in technology lead to the emergence of new solutions and lower hardware prices, which potentially makes the architecture of information systems more flexible. At the same time, the interoperability and openness of software and hardware products from different manufacturers are expanding, although so far their efforts aimed at compliance with standards have been coordinated only in narrow market sectors.
Today, the key scalability parameters are
flexibility of architecture.