On 02/12/2013 16:24, Brian Inglis wrote:
[]
When I ran current stable under Win 7 with only network servers I found
I had to drop minpoll to 4 (default is 6) so iburst would quickly get
a good offset and pull drift down from initial out-to-lunch estimate
compared to drift file contents.
Once drift got pulled down close to hardware levels, poll would increase
and further pull down offset < 10ms, then at longer poll intervals,
both drift and offset would slowly get more accurate over a period of
about three weeks.
About then patch Tuesday would come around and it would be back to
square one!
I had to ensure BIOS spread spectrum and OS power saving were turned off
and pick servers that were not busy, with no drops or steps, delay < 90ms,
jitter < 20ms, offset < 10ms.
As pings were often blocked, I used traceroute (tracert on Windows) to do
initial delay estimates, when those were not also blocked in a DMZ, and
tried ntpq -p -c rv -c cv as a final check out when possible.
I try to pick about four good quality servers which may be quite distant,
but within the criteria above, and four decent fairly local servers for
those times when interconnects fail and only local servers are reachable.
One thing I have noticed is that my NTP clock (HPET) is being reported
as having ~28PPM drift where my hardware is only ~.9PPM!
.. which all seems a lot of effort compared to getting your own
stratum-1 server with no soldering for around US $150:
http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html
http://ava.upuaut.net/store/index.php?route=product/product&path=59_60&product_id=95
--
Cheers,
David
Web: http://www.satsignal.eu
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