Economies of Non-Scale
Scalability forces us to think differently. What worked on a small scale doesn't always work on a large scale -- and costs are no different. If 90% of our application is free of contention, and only 10% is spent on a shared resources, we will need to grow our compute resources by a factor of 100 to scale by a factor of 10! Another important thing to note is that 10x, in this case, is the limit of our ability to scale, even if more resources are added.
1. The cost of non-linearly scalable applications grows exponentially with the demand for more scale.
2. Non-linearly scalable applications have an absolute limit of scalability. According to Amdhal's Law, with 10% contention, the maximum scaling limit is 10. With 40% contention, our maximum scaling limit is 2.5 - no matter how many hardware resources we will throw at the problem.
This post discuss in further details how to measure the true cost of non linearly scalable systems and suggest a model for reducing that cost significantly.
