Sure, just duplicate your entire stack in at least two zones and replicate all data in realtime, and then you just need to convince your boss/investors/yourself

Sure, just duplicate your entire stack in at least two zones and replicate all data in realtime, and then you just need to convince your boss/investors/yourself that spending 2X on hosting is worth it. Once you add up the costs you soon realize that risking several hours of downtime once per year is more acceptable than doubling hosting costs. For anyone who is not hosting air traffic control or banking systems it's really not worth it. Seriously, if your web service is hosting social brain farts or selling cup holders, and not landing a space shuttles, then it can be offline a for few hours per year.