Scalability in a system is about the ability to do more, whether it is processing more data or handling more traffic, resulting in higher transactions. By definition, scalability poses great challenges to database and transaction systems. At some point, either due to practical, fiscal or physical limits, enterprises are unable to continue to "scale out" by simply adding hardware.
WXS attempts achieving scalability by providing a network attached fabric that holds the data in form of objects. First, it improves database performance since only select entities connect to the database. Second, it improves application performance by moving data closer to the application.
You shoud also look at CAP theorm.
:)
Nitin