An example of an application that does not work well in asimple cloud environment is a shared database, such as the typical Oracle database application, where the information is one big block of data that needs to be manipulated all the time by many computing processes and where access to the shared data needs to be synchronized and managed.
Millions of simultaneous users play Farmville or Draw Something (which scaled up to 36 million users in 6 weeks), which requires asimple, fast, elastic database (called a NoSQL database, a new category of product designed for the age of big data), that can process and deliver massive amounts of user and other types of data in real time.