Galileo observed how things broke if they were naively scaled up.
Google found the larger the scale the greater the impact of latency variability. When a request is implemented by work done in parallel, as is common with today’s service oriented systems, the overall response time is dominated by the long tail distribution of the parallel operations. Every response must have a consistent and low latency or the overall operation response time will be tragically slow.
Fantastic post from Todd Hoff on the (hopefully) well known truth: “the reponse time in a distributed parallel systems is the time of the slowest component“.
Original title and link: When More Machines Equals Worse Results ( ©myNoSQL)