dmv wrote:

Jeremy Wright purports a common misconception about new companies doing business online: That you need 99.999% uptime or you’re toast. Not so. Basecamp doesn’t have that. I think our uptime is more like 98% or 99%. Guess what, we’re still here!

Wright correctly states that those final last percent are incredibly expensive. To go from 98% to 99% can cost thousands of dollars. To go from 99% to 99.9% tens of thousands more. Now contrast that with the value. What kind of service are you providing? Does the world end if you’re down for 30 minutes?

A common misconception by business people and IT alike. You don't need five 9's of protection even if you ARE WalMart, cuz the cost to get there is huge (providing diminishing returns on investment) and you will have a website that only has about 8.7 hours of downtime per year (including leap years). Considering that most websites need to come down for periodic maintenance (scheduled downtime), this is probably not worth it. The only systems that are six 9's are air traffic control and high end military. Even telecom isn't that high. Then you get about 45 minutes of downtime for the year at extraordinary cost.