nine

n. in a percentage between 99 and 100, a place on either side of the decimal point given a value of nine and counted in serial to indicate a number very near 100 percent, such as in measurements of reliability, accuracy, purity, etc. Subjects: English, Technology, Jargon

Editorial Note: Common forms are five nines, meaning 99.999%, and six nines, meaning 99.9999%. Also used attributively: the company offers five-nines reliability guarantees.

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Citations: 1918 Preparation of NBS White Cast Iron Spectrochemical Standards “United States. National Bureau of Standards”: The copper was OFHC grade; the zinc was five nines pure. 1962 American Society for Metals Ultra-High-Purity Metals p. 2: Electromet silicon of less than three-nines purity, the purest available at the time, provided at a cost of $16 per pound. 1981 U.S. Congress Technical Advisory Panel on the Digital Data Communications Network: Hearings p. 130: If you take 2600 terminals, each with a reliability of three nines and you figure it out, you find that the entire system probably is on the order… 1985 William E. Clayton Jr. Houston Chronicle (Texas) (Apr. 11) “U.S. urged to hurry waste disposal plans” p. 1: One proposal is to require that the most dangerous substances be burned 99.9999 percent—the “six nines,” the company calls it. 1991 [Kieran A. Carroll] Usenet: sci.space (Mar. 12) “Re: German conference highlights doubts about ESA’s manned space plans”: What level of reliability do you want to design into the satellite, and verify via ground testing? 99%? Or three nines? Or four? 2003 [Jonathan A. Zdziarski] Full-Disclosure email list (Nov. 16) “Spam and ‘undisclosed recipients’”: Within the past week, our collective system has caught an additional 40 spams that would have otherwise gotten through. Clearly it is proving itself to be helpful in A. breaking down the isolation barrier between statistical-based filter users, and B. helping to mudge past three-nines accuracy. 2006 David S. Isenberg Isen.blog (Apr. 7) “Verizon owes me 1365 years of perfect service”: My phone line has been out—completely out, no dial tone—for 2 days since I discovered and reported the outage. If “five nines” were a guarantee, that is, if it had any reality to it at all, I could expect 100,000 days, or 274 years, of perfect service for each day my phone were out, or 548 years total. 2006 Jeanne Lim @ Singapore ZDNet Asia (June 21) “VeriSign expands networks in Asia”: Priding itself on its “five-nines” reliability pedigree—VeriSign’s uptime performance of running dot-net and dot-net is 100 percent—the company is guaranteeing the same reliability for operator customers.

Posted 21 Jun 06 | Permalink | Tell a Friend