Availability
Electrical Grids
- U.S. Electrical Grid Gets Less Reliable – spectrum.ieee.org/energy/policy/us-electrical-grid-gets-less-reliable
- U.S. Power Reliability: Are We Kidding Ourselves? – tdworld.com/grid-innovations/article/20966117/us-power-reliability-are-we-kidding-ourselves
- “For example: “The average U.S. customer loses power for 214 minutes per year. That compares to 70 in the United Kingdom, 53 in France, 29 in the Netherlands, 6 in Japan, and 2 minutes per year in Singapore. These outage durations tell only part of the story. In Japan, the average customer loses power once every 20 years. In the United States, it is once every 9 months, excluding hurricanes and other strong storms.”
- US: 214 min/yr (~ 99.9593% availability, close to “3.5-nines”)
- UK: 70 min/yr (~ 99.9867%, approaching 4-nines)
- France: 53 min/yr ( ~ 99.9899%, closer to 4-nines)
- Netherlands: 29 min/yr (~ 99.9945% about 4.5-nines, quite impressive)
- Japan: 6 min/yr (~ 99.9989%, basically 5-nines, very impressive!)
- Singapore: 2 min/yr (~ 99.9996%, how to they do it?)
- “For example: “The average U.S. customer loses power for 214 minutes per year. That compares to 70 in the United Kingdom, 53 in France, 29 in the Netherlands, 6 in Japan, and 2 minutes per year in Singapore. These outage durations tell only part of the story. In Japan, the average customer loses power once every 20 years. In the United States, it is once every 9 months, excluding hurricanes and other strong storms.”
“Five Nines”
99.999% (“5 Nines”) uptime, means less than 5.26 minutes downtime on a year-basis.
Telecom
- “5 nines” has been a goal for uptime in telecommunications networks for decades, .e.g. (wikipedia references):
- Plain Old Telephone Service (POTS), Public Switched Telephone Network (PSTN), and Public Safety Networks
- Sometimes hard requirement (internal key performance indicators) but overall sometimes more a goal than harder requirement
- google.com/search?q=telecom+availability+standards
- en.wikipedia.org/wiki/Category:Telecommunications_standards
How Achieved
How the telecom industry is able to provide high availability systems is illustrated by the following figure:
Key components for achieving high availability solutions include:
- Backups (in this case alternative power sources like batteries, generator, wind, sun, …)
- Support systems like
- Access control and security, to prohibit unwanted visitors
- Climate control for equipment
- Fire detection and suppression
- Monitoring, and remote control – periodic tests of batteries, remote running of generators, and such)