Comment by Spearchucker

12 9s is new to me too. Not worked on anything better than 5 9s (5 mins downtime/year), and Wikipedia only goes to 9. 9 9s comes to 35ms downtime a year. I can't think of anything that needs more than 5 9s, let alone 9.

http://en.wikipedia.org/wiki/High_availability#Percentage_ca...