[ntp:questions] Ignore one server except in extreme conditions?
agcarver+ntp at acarver.net
Wed Nov 16 07:47:32 UTC 2011
On 11/15/2011 23:28, Harlan Stenn wrote:
> OK, and you understand that the NMEA sentence is expected to be correct
> to only +/- 0.5sec, as the PPS signal is un-numbered and the purpose of
> the NMEA data is to identify the time at the pulse of the PPS signal.
Yes, the PPS is unnumbered however if I have valid and reachable
Internet server then I have numbers from them, too. PPS is only serving
as the clock tick, I understand that fully. But you're missing the
point of my question:
I don't care about the exact accuracy of the NMEA. I mention the NMEA
to point out that it is unstable and I would like it to not be part of
the timing computations unless no other server is available. That's
what I'm asking. If I use the "noselect" option, it is never a valid
time server no matter what. If I use "prefer", it's always a valid time
server. I'm asking if there's a way to configure ntpd such that
everything EXCEPT NMEA is a preferred peer unless all the other peers
are dead in which case fall back to NMEA (all predicated on the GPS
being functional, if not that's a completely different issue).
Right now, it is almost always part of the valid group of servers. It
is never marked as a false ticker or an outlier even if its data is
terrible compared to any of the other five configured Internet servers.
More information about the questions