[ntp:questions] Odd (mis)behavior when reference clock fails

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Tue Sep 23 21:19:27 UTC 2008


>It's 4.2.4p4 running on FreeBSD 7.0. The reference clock is a EndRun
>Tech CDMA clock using the TrueTime driver. When the system was running,
>ntpq claimed no successful polls of the reference clock or the PPS. It
>was getting good responses from other systems, but not syncing to
>them. The offset started small after the clock failed, about .003, and
>steadily grew to over 5 ms. The reference clock always showed a zero
>reachability, delay and offset and .001 jitter.

Do you have a good collection of old log files?

How about deleting the drift file and restarting ntpd?

I've seen ntpd get confused when the drift on the system it's running
on changes by a big step.  I can't think of why a clock dying would
cause that sort of change, but I don't have any better suggestions.

I have a Linux box that changes by almost 200 PPM when I turn a
program on/off.  That program does a lot of serial port activity.
(It's polling a UPS as fast as it can.)  I haven't tracked it down.
I hope FreeBSD doesn't have quirks like that.

-- 
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