HOW MUCH UPTIME CAN I AFFORD?

Summary from the TLDR Web Dev newsletter

Engineering for 99.5% uptime is much more cost-effective than 99.99% for most startups. This is because in order to achieve that level of reliability, you will need specialized architecture, redundant infrastructure, and streamlined operational and organizational procedures. The cost comes in terms of system complexity, the number of engineers required and their specializations, experience levels, and corresponding salaries, as well as significantly increased operational costs and arrangements. 99.99% guaranteed uptime must be 50 times as reliable as one with "only" 99.5%.