Businesses today are developing high traffic web applications that serve tens of thousands or even millions of concurrent users. A Majority of these applications are developed in Java and deployed in a load-balanced web farm consisting of Linux or Windows servers.
In such a high traffic environment, two things are very important. First is that your application performance should maintain response rates even under peak loads (scalability) and secondly, your application should stay up all the time and should not crash (high availability).
Read more on In-Memory Key Value Store.