Running MongoDB effectively on AWS is very expensive. It&#x27;s the opposite of what AWS is optimized for. It requires a dedicated amount of RAM that scales with your database, and it requires permanent storage that&#x27;s about 100x the size of the actual data.<p>It&#x27;s very much unlike a nice, bursty, CPU-bound web server.<p>Also, you can&#x27;t use the big selling point of AWS, which is that you can scale it &quot;elastically&quot;. Okay, you <i>could</i>, but it would be a terrible experience with lots of unavailability.