3 ms·
each 9 you add past 99% costs more than the last. You're right about that. In fact, each 9 past 99% costs twice as much as the last. But on the other hand wh
by byoung2 16y ago
each 9 you add past 99% costs more than the last.
You're right about that. In fact, each 9 past 99% costs twice as much as the last. But on the other hand when you have paying customers, one day of downtime they might forgive you. Two days and they'll be annoyed. But on the third day they'll come for you with pitchforks in hand. If you can avoid pitchforks with clever architecture and slightly higher costs, I think it's worth it.
- nostrademons 16y agoIs it only twice? In my experience, 99.9999% uptime is significantly more than 16x more expensive than 99% uptime. For comparison, 99.9999% uptime means about 30 seconds of downtime in a year, while 99% uptime is about 3 days of downtime. You can get 99% uptime with a singly-homed, not terribly reliable commodity system. For 99.9999%, you need multiple redundancies in every architectural component with automatic error detection and failover, and have to watch every change to make sure it doesn't introduce the possibility of system instability or cascading failures. Those are qualitatively different approaches to software engineering.