Wednesday, 22 January 2020

What is 99.99% of Availability?

Service/Application Availability is defined by uptime. I.e. the time between failures. It is dependent upon

Downtime  - the amount of time the system is unavailable due to either failures or scheduled maintenance.

Recovery time - the average time it takes to recover from failures. 

Hence to have high availability, you must have low downtime and low recovery time.

What's 4 nines(99.99%) of availability? In simple math:

99.99% availability = (365*24*60) - (365*24*60*99.99/100) = 52.56 minutes = 52 minutes and 30 secs

Seven-nines or 99.99999%  - availability means 3 seconds or less of downtime in a year
Six-nines or 99.9999% - availability means 30 seconds or less of downtime in a year
Five-nines or 99.999% - availability means 5 minutes, 15 seconds, or less of downtime in a year
Four nines or 99.99% - availability allows 52 minutes, 33 seconds downtime per year
Three nines or 99.9% - availability allows 8 hours, 46 minutes downtime per year
Two nines or 99% - availability allows 3 days, 15 hours, and 40 minutes downtime per year.

Thanks!!! Enjoy Programming!!


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