It’s all in the math.

I was recently talking to a collegue about web hosting, and the expression “99.9%” up-time came up. He was adminant about having a solution that had 99.9% up-time due to the crucial need for his site. I told him 99.9% really doesn’t mean much, and he disagreed. We looked at the hosts “promise” and noticed that the 99.9% up-time was within one year. This means that in any one year his hosting will be up 99.9% of the time. So, let’s break that down…

There are 365 days in a year. There are 24 hours in a day. This breaks down to 8,760 hours in a year. If we go by hours, 99.9% is 8,751. That means that his site could be down for 9 hours in any given period of 365 days.

Break it down further to minutes, and that’s 540 minutes. Most people can’t stand their site being down for 5 minutes. So 99.9% up-time means that if his site is down for 1 hour, they (the host) are still within their service agreement.

Even if the agreement stated 99.9% up-time per day, a day is 1,440 minutes. 0.1% down-time is 14.4 minutes a day.

In the end, he understood what I meant. Sometime we need to look beyond the promise to the actual math.

Okay, I know we all hate math, but the truth behind this is … think of all the things in our lives that are promoted as 99% effective. Perfection may be unattainable, but it doesn’t mean we should stop trying.

Class dismissed.

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