99.9% sounds nearly perfect. It's actually 8 hours and 46 minutes of annual downtime—and the number hides even more than it reveals.
Each nine in availability represents ten times less downtime—and exponentially more organizational transformation. A guide to what each level actually demands.
SLOs define what 'good enough' means for your service. SLAs are the promises you make when money is on the line. Error budgets are the insight that makes both useful.
SLIs measure what users actually experience—not what your servers report. Learn to choose metrics that reveal reality, not comfort.
Error budgets flip reliability engineering on its head: instead of preventing all failure, they give you a failure allowance and ask whether you're spending it wisely.
Every system fails eventually. Redundancy buys you time between failure and impact. Failover determines how much time you actually get.
Active-passive bets that failure is rare. Active-active bets that failure is routine. Both bets are correct—depending on your scale. Here's how to choose.
Your assumptions about system resilience are probably wrong. Chaos engineering is how you find out before your customers do.
Every 'works on my machine' bug is an invisible assumption—something you didn't know you were depending on. Here's how to see them before production does.
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