I like the way MongoDB describes the flaws in their own system, but places the blame (four) squarely on the customer, where it belongs. It wasn't a random fail

I like the way MongoDB describes the flaws in their own system, but places the blame (four) squarely on the customer, where it belongs. It wasn't a random failure or a sudden spike that caused the crash -- it was completely predictable growth. Foursquare had already experienced the problem once, and they had solved it. All they needed to do was monitor their growth and iterate that solution. Sure, Foursquare could have had a better sharding algorithm, but that would only have put off the crash a bit longer. This is a very basic failure -- not monitoring a system that you know is steadily growing.