Here is Wikipedia‘s handy chart of the pursuit of nines:
Interestingly, only 3 of the top 20 websites were able to achieve the mythical 5 nines or 99.999% uptime in 2007. They were Yahoo, AOL, and Comcast. In the first 4 months of 2008, some of the most popular social networks, didn’t even come close to that.
From the chart, it should be evident how ridiculous the pursuit of 100% uptime is…