on 3/16/09 12:31 AM, [email protected] said: > actually, IMHO, you didn't explain very much at all in your article, you > basicly stated that any competent person would know why having two NTP > servers is worse than having one (with no information or links explaining > your reasoning for this),
The editors screwed up the article and didn't include my footnote. See section 5.3.3 of the page at <http://support.ntp.org/bin/view/Support/SelectingOffsiteNTPServers>. > P.S. there is a _very_ good reason for configuring systems to point at two > NTP servers instead of one, Unfortunately, this is one of the more common misconceptions. It all has to do with the way the NTP peer selection algorithm works. It never averages numbers. It is designed to throw away the two outliers from the geometric mean (the highest and the lowest), and then see who is left. It keeps doing this until it gets down to one clock that is closer to the geometric mean than any other. When you have only two upstream clocks, neither of them can be closer to the mean than the other, and then you're off into LaLa Land where anything whacky could potentially be done and probably is being done billions and billions of times around the world on a daily or even hourly basis. > it means that the clocks will remain synced > much better if one NTP server dies rathat than having them all go off in > their own directions. the time may not ever be as precise as the single > NTP server case, but it's good enough for almost all real-world > applications. Unfortunately, this claim is demonstrably wrong. And the fact that you claim it is correct just goes to show the level of misunderstanding, misconceptions, and misinformation that keeps getting propagated on a daily basis. I'm sure you didn't intend to propagate a misconception, but that doesn't reduce the damage you may have already done over the years by telling people this same story, time after time. -- Brad Knowles <[email protected]> If you like Jazz/R&B guitar, check out LinkedIn Profile: my friend bigsbytracks on YouTube at <http://tinyurl.com/y8kpxu> http://preview.tinyurl.com/bigsbytracks _______________________________________________ Tech mailing list [email protected] http://lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
