99.999% Reliable? Don’t Hold Your Breath

Randall Stross:

At my house, the Internet connection is flaky at times, so I really shouldn’t demand that my favorite Web sites have Five-9s availability. Perceived reliability is determined by the least reliable service in the chain. A home user’s Internet connection, with a laptop using Wi-Fi, would be available about 99.8 percent of the time, estimates Mr. Hölzle at Google, which equates to about 18 hours of cumulative downtime a year. So, he says, “if Google provided Five 9s, you wouldn’t know.”

With my current Internet service provider, I’d be surprised if I received 99.8% uptime last year. Even so, the point remains the same. Service providers on the Internet, be it e-mail, storage, or otherwise, are striving for and coming quite close to a reliability that consumers will expect in the future.