For reference, 99.999 is 5 mins of downtime/year. 99.99999 is 3 seconds of downtime/year. As you get beyond 5 nines, environmental factors begin to dominate (

For reference, 99.999 is 5 mins of downtime/year. 99.99999 is 3 seconds of downtime/year. As you get beyond 5 nines, environmental factors begin to dominate (if the service is networked: network unavailability, if the service is onsite, power outages and weather) any reliability inherent in the service.