The Computer Corner
By Charles Miller April 25, 2008 San Miguel de Allende

Five nines worth millions 

In a recent column I used a word one reader did not understand. The Atención reader asked, “What is uptime?” Webster’s does not shed much light on the definition, and if you ask a techie, “What is uptime?” the answer will probably be “It’s important!” So what is “uptime” really? It is defined as being the time that something is available and operating and strangely enough, it is the opposite of “downtime.”

The gold standard of uptime is referred to as “five nines” or 99.999 percent. This is a rare but achievable goal somewhat like the “perfect game” in baseball (there have been only 17 perfect Major League baseball games in 131 seasons).

Let us take a closer look at the numbers: 99.999 percent means that there was a mere 5 minutes of downtime in a year; 99.99 percent equals one hour of downtime over the same year while 99.9 percent is eight hours out of the year. If service is unavailable for about four days out of the year, that is 99 percent uptime and if you experience a week of downtime, the uptime is still 98 percent.

Most companies doing business on the internet strive for 99 percent uptime and the reason for this number involves both common sense and financial considerations. While it is desirable to have “five nines,” the fact of the matter is that many businesses that have crunched the numbers realize that the world does not come to an end if their website is offline occasionally, and that those extra nines are incredibly expensive to obtain.


A rule of thumb says that every decimal point of uptime equals another decimal point in cost. For a business this means that if their internet access or website had 99 percent uptime and cost a thousand dollars a year, taking it up to 99.9 percent uptime could well cost ten thousand dollars and 99.999 percent might be a million. Business managers who look realistically at the costs involved are almost always going to come to the decision that buying five nines is neither affordable nor necessary.

So what does all this mean for the average home internet user? As I pointed out in the earlier column, my unofficial statistics showed that my internet connection provided by the local cable company had achieved 99.6 percent reliability costing me less than 400 pesos a month. There are things I could do to improve that reliability, but all those things would end up costing me more.

During a recent daylong outage I received a phone call; actually I got a lot of calls that day. This particular caller was whining about how lousy she thought her service was and asked what could be done about it. I pointed out the facts, that she was already getting over 99 percent uptime, then took time to explain some of the things she could do if she were willing to spend more. Like me, she was not interested in paying more.

So, the bottom line here is that both the typical home internet user and most companies doing business on the web are going to realize that if their internet connection goes out for a few hours the world is not going to come to an end. Uptime is vital to some folks—eBay or Amazon.com losing a connection would be the end of the world (at least for some manager or technician who gets fired). That is why those companies pay millions of dollars to buy all five nines.

My advice is to not worry about this. Worry about uptime where there is reason to worry about it. Until then, be glad that in San Miguel de Allende we are able to get very reliable internet service for a very reasonable price.

Charles Miller is a freelance computer consultant, a frequent visitor to San Miguel since 1981 and now practically a full-time resident. He may be contacted at 044-415-101-8528 or email FAQ8 (at) SMAguru.com.
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