"Have you heard the phrase "You're not Google, you're not Facebook, and you're not Netflix"? The TL;DR; is those tech giants that have 1M+ concurrent users. They have a hard requirement for no downtime."
Actually, one of the more interesting parts of the Google SRE book was that they don't try to aim for 0 downtime. They consider the background error rate of any network request and optimising much beyond this is counter productive.
Even for individual services they make a point of not trying to make them perfectly available, as this means downstream services are less likely to build in adequate provision for failure.
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"Have you heard the phrase "You're not Google, you're not Facebook, and you're not Netflix"? The TL;DR; is those tech giants that have 1M+ concurrent users. They have a hard requirement for no downtime."
Actually, one of the more interesting parts of the Google SRE book was that they don't try to aim for 0 downtime. They consider the background error rate of any network request and optimising much beyond this is counter productive.
Even for individual services they make a point of not trying to make them perfectly available, as this means downstream services are less likely to build in adequate provision for failure.
I agree with this.
Those tech giants got to where they are by recognising specifically that they don't have "no downtime" requirements.
"Move fast and break things" isn't the mantra of companies with zero downtime requirements.
Choose how many nines you want. For most 99.9% availability is probably OK.