[ntp:questions] Meinberg NTP monitor, silly question

Richard B. Gilbert rgilbert88 at comcast.net
Tue Dec 22 19:37:48 UTC 2009


unruh wrote:
> On 2009-12-22, Richard B. Gilbert <rgilbert88 at comcast.net> wrote:
>> David J Taylor wrote:
>>> "G8KBV" <g8kbv at nospam-uko2.co.uk> wrote in message 
>>> news:MPG.2599f4f8b90958d1989692 at news.demon.co.uk...
>>> []
>>>
>>> You will find that for the best performance, the NTP PC needs to be left 
>>> running, as initial settling is not quick.
>>>
>> "Not quick" is an extreme understatement!  It takes about 30 minutes to 
>> get a "reasonable approximation".  It can take ten to twelve hours to 
>> stabilize with the best possible approximation of the time.  Once there 
>> it's good for as long as you can keep the power on and the temperature 
>> reasonably stable.
> 
> Yes, the time scale is about 1 hour half life (it takes about 1 hour to
> halve the error). David Mills gets really
> annoyed if someone points out how slow ntp is at converging. It is
> definitely a feature, not a bug. That you or I could, with the first
> three offset measurements, make a far better approximation to the true
> time and rate than ntp does, is irrelevant. 

Well, you could always try to create an NTPD that would converge more 
quickly without introducing some other nastiness.  Somehow I think this 
would be a massive project and is quite likely impossible.  If Dave 
Mills thinks it won't work he's probably right.

Keeping an NTPD server up and synched is not all that difficult.  A UPS 
will keep you alive for three to fifteen minutes if power fails.  The 
longer the UPS run time, the more it costs.  Any longer than fifteen 
minutes and you will need a generator fueled by either gasoline or 
natural gas.  You will either need a human being to start it and set it 
for the right speed or a device that will do this automagically.






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