James Hamilton on Zynga shutting down data centers and moving back to AWS ( emphasis mine ):
These days, there is more data available and it’s fairly easy to show that “being at scale” requires order 10^6 servers, deep investments in server and networking equipment and the software stacks above, and massive investments in the software stack that manages these resources.
You read that correctly, if you have fewer than 1,000,000 servers you are not “at scale”.