Andrew Harrison wrote:
On Thursday, August 1, 2019 at 7:43:32 AM UTC-4, Terje Mathisen
wrote:
I ran the ntp setup for Norway's largest multinational corporation
for 20+ years, my final setup used dedicated
TrueTime/Symmetricom/Meinberg gps-based servers in 3 main
locations, augmented with radio-based clocks in a couple more as
well as several hand-made FreeBSD servers using Oncore and SURE
evaluation boards with timing gps receivers.
All these primary sources were used as references for a second
layer of dedicated Stratum 2 servers, two in each of those 3 main
geographical centers, and with identical/symmetrical conf files.
The latter works because an ntpd server automatically omits any
circular reference, to itself or another source.
Finally, every single client machine capable of running the full
ntpd stack was configured to use all 6 Stratum 2 servers as their
reference, this provided enough redundancy that we never suffered
any visible hickups even when we passed through the GPS week
rollover or when an individual reference server lost a leap second
event.
Except for the hardware ref servers, this was all effectively close
to zero cost, only some labor hours.
Sounds similar to what my eventual plan is, once I get this working.
The Symmetricoms will be accessed by only two servers running ntpd.
All other devices will pull time from those two servers, they won't
talk to the Symmetricoms directly.
I just need to figure out how to get ntpd to notice and behave
appropriately when the Symmetricom stops advertising itself as
stratum 1.
I suspect your "prefer" option (which I think you reported using?) might
be the culprit? Have you tried your setup without any indications of
which serer(s) to prioritize?
We now have a support contact with Syncworks and one of their guys
has been trying to figure this out with me as well, including him
reaching out to some of his contacts at MicroSemi. No luck so far,
but it isn't looking good since this is starting to feel more like a
bug in ntpd.
What happens to the dispersion figure when you remove the antenna?
If you have logging configured then you should be able to see how this
is handled: YOur client machines should notice that the other server has
much higher quality even if the stratum level is the same (and even if
this is really a bug).
Frustrating, since this will probably all be moot next year. I have
to get another year out of our Symmetricoms before we can buy new
ones that aren't well beyond EOL.
Good luck!
Terje
--
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"
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