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Comment by jsnell | Hacker News Reader

> We strive to engineer systems that are highly available and fault-tolerant and we expect that most of these monthly updates will recap periods of time where GitHub was >99% available.

So that's them striving for two nines most of the time, which seems to be a fancy way of saying one nine. Be careful you're not setting the bar too high!

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That doesn’t seem to be what it’s saying. Wording is unclear, but it seems to be saying that _for the incidents recounted in these updates_, most of the time the GitHub service itself will be 99% available. That’s not the same as saying they only strive to make GitHub 99% available at all times.

Hm. Not sure I see that. The updates are monthly, so the period of time they're recapping will be the last month. And they're expecting that on "most" recapped periods the availability was >99%. I.e. they also expect to have months where availability is <99%.

a key distinction! I favor your interpretation

That number stands out more than anything else in that report.

99% availability effectively becomes the weakest link in the chain. Would they still have pushed this report out if they phrased it as "...where GitHub was only down for an hour for every 99 hours of uptime"

Also this is like South Africa Post Office. 99.9% of packages delivered! = you lost 0.01% of them which totalled millions.

I always heard that the number of nines was after the point, so that'd be zero nines. Two nines would be 99.99%

That's wrong. Five-9's for example, is 99.999% uptime, or a bit over 5 minutes downtime per year.

Maybe you're thinkinng of the actual proportion value. 99% can more simply be written as 0.99, which is two nines after the true decimal point.

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