it's the 2 nines they aimed for
1-4 incidents per month compared to about 1 daily.
Like they are down to one 9 availability and very very close to losing that to (90.2x%).
This also fit more closely to my personal experience, then the 99.900-99.989 range the article indicates...
Through honestly 99.9% means 8.76h downtime a year, if we say no more then 20min down time per 3 hours (sliding window), and no more then 1h a day, and >50% downtime being (localized) off-working hours (e.g. night, Sat,Sun) then 99.9% is something you can work with. Sure it would sometimes be slightly annoying. But should not cause any real issues.
On the other hand 90.21%... That is 35.73h outage a year. Probably still fine if for each location the working hour availability is 99.95% and the previous constraints are there. But uh, wtf. that just isn't right for a company of that size.
- at most 20min per 3 hour
- and 99.9% uptime on a yearly basis
as in your yearly budged of outage is ~8.76h but that budged shouldn't happen all at once and if there is an outage it at most delays works by 20min at a time, and not directly again after you had a downtime
but I did fumble the 90.21% part, which is ~35.73 days i.e. over 857 hours....
Days, not hours.