On When To Scale

It's never clear cut when you should scale in advance or if you ain't gonna need it.

At Amazon, in my capacity as a principal engineer, I was often the bad guy.

"This design won't scale," was a common refrain of mine. I would then launch into a laundry list of why their approaches wouldn't work.

At Prime Video, my last team, we had an assumption of scale. We serviced hundreds of millions of customers in nearly 200 countries. We served video content, which required a ton of bandwidth. While we weren't the biggest streaming service, we did account for a substantial proportion of ALL packets on the internet. Amazon Prime, the subscription service that gives access to video, is one of the best-selling products of all time.

Adding features or capabilities to this product required that we do a lot of extra work to ensure high availability to our customers under load. You can't just roll something out and pull it back if it doesn't work. You…