Those 9's <i>stack</i>. Doesn't matter how good your reliability is, when your ISP gets blown away by a tornado, or the phone company takes a week to diagnose a backhoe bite.<p>Construction (and others) price some things in cost per <i>operating</i> hour; where IT seems to have taken a militant attitude of "all hours are operating hours." Equipment working an 8hr / 5 day shift has "maintenance windows" built in and can be held to a higher standard for on time vs off time.