[ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.

Ron Frazier (NTP) timekeepingntplist at c3energy.com
Tue Mar 13 16:52:49 UTC 2012

Hi all,

I just woke up to a 50 SECOND clock error.  Prior to the error, with my 
PC locked into the GPS and the internet servers noselected, here's what 
my peerstats looked like.  Baseline is the GPS.  Colored lines are 
internet servers.


Here is what was showing on the Meinberg Time Server Monitor when I woke up:


And the graph of the peerstats for that time:


The clock error was REAL, as confirmed by my atomic wrist watch.

However, the loopstats graph for the same time period shows no problem 
with the GPS:


So, I shut down NTPD and reset the time with a batch file that calls 
ntpdate and querys the New York NIST server:


Here is the time server monitor shortly after NTPD restart:


And after a 2nd restart:


And here are the current peerstats, which look normal.  The offset to 
the internet servers tends to drift and will eventually cross the zero 
line and get positive.


The GPS appears to have been stable all through this, and was never 
powered off or unplugged.  It looks like NTPD went crazy and reset my 
clock for some reason.

Here are the peerstats and loopstats during the insane period.


Here is my current ntp.conf:


My system is Windows 7, NTP 4.2.7p259, GPS GlobalSat BU-353 USB NMEA 
only with GPGGA sentence at 57,600 baud.

If anyone can shed some light on what happened, please do.  It's driving 
me bonkers.  I don't believe the GPS is at fault, and I suspect NTPD.

Thanks in advance.




(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such.  I don't always see new messages very quickly.  If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)

Ron Frazier
timekeepingdude AT c3energy.com

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