4.2 Chain Reactions
In Defining Capacity, I’ll talk a lot about the two main flavors of scalability: horizontal and vertical scaling. Horizontal scaling refers to adding capacity by adding servers. This is the Google and Amazon approach. A web farm is an example of horizontal scaling—each server adds nearly the same amount of capacity as the previous server. The alternative, vertical scaling, means building bigger and bigger servers: replacing x86 pizza boxes with four-way, eight-way, and then thirty-two-way servers. This is the approach Oracle would love to see you use. Each type of scaling works best under different circumstances.