100 Things: #21

[pyran]

The industry standard of "Five Nines" with regard to service uptime is that an online service should be up for 99.999% of the year.  This means the service is allowed 5.26 minutes of downtime per year.

Change that to Six Nines (99.9999%), and the amount of allowable downtime drops to 31.5 seconds per year.

Comments

[fishsupreme]

99.999% uptime allows for basically one reboot per year, which makes patching vulnerabilities every month pretty difficult. Pretty much the only way to maintain it is 100% redundancy -- that is, have no single points of failure in the entire service, up to and including hosting a replica in an entirely different physical location.