Hacker News Reader

Comment by bak3y | Hacker News Reader

I've always heard that adding another 9 adds another 3 zeros to the cost.

IME many companies claim 99.99+ uptime but then the penalties are trivial. If a 99.99 SLA is busted with an hour of downtime in a month but the penalty is 5% bill credit, the company just lost $500 on $10k revenue, assuming that:

A) Customers actually chase the credit, which (again IME) many companies make very difficult

B) The downtime is very clearly complete downtime. I've seen instances where a mobile app is completely down (but the web product works) or a key API is down (but the core product works) or there are delays in processing data (but eventually things are coming through). All of these can cause downstream downtime to customers but may not be covered by a "downtime" SLA.

Once a company claimed nine 9s (99.9999999%, 0.03 seconds down per year) uptime on their new cloud service to me. When pressed how they came up with the number their measurement they said they were measuring the percentage of time the login webpage loaded (not that you could log in or things worked inside the page and app) and the https://uptime.is/ tool only went up to nine 9's.

We need nine 5s of uptime. 55.5555555% uptime AT LEAST.

At one dollar for 99 that's a billion dollars for 99.999. Seems a bit extreme on each end for a three 9's difference.

For anyone wondering, 0.001% of downtime a year is 5 mins 16 secs.

I like the mnemonic that five 9s is five minutes a year.

Reply on news.ycombinator.com