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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!!

 Reference:

 https://blog.hike.in/4-9s-b1fc497f3de2
https://vikashazrati.wordpress.com/2008/10/24/truth-about-availabilit/

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Location: Bengaluru, Karnataka, India

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