Reserved Instances: Use It or Lose It
Reserved instances are one of those things that, when you first hear about them, you say, “Wow! I could save a lot of money!” And then you start to try and figure out how many you need? What sizes? Which operating systems? In which regions? Should they be convertible? Should I choose a 1-year or 3-year term? All up-front, partial up-front, or no up-front? How much compute am I actually going to need over that term?