My take on their experience was that they had only sort of abstractly thought about stability. Then they severely underestimated the variance in performance.

My take on their experience was that they had only sort of abstractly thought about stability. Then they severely underestimated the variance in performance. Before moving to Amazon, stability was something you worked at in the lower levels, e.g., hardware, power, etc. Once you move to amazon, stability cannot be controlled at a lower level, so you have to make your application code more robust. With your own IT infrastructure, you'd logically put the focus into improving the reliability on your hardware stack, rather than just focusing on handling those issues in software.