Re: [chrony-users] Chrony source selection algorithm documentation

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Hey Miroslav,

thank you for the explanation. If the switch will happen eventually
(once the estimated error got big enough) that behaviour is good for my
purpose.
Does the refclock parameter "precision" have an influence on how soon
the gps is considered better than the offline servers?
I have it set to "precision 1e0" at the moment. Would you recommend a
different setting?

Greetings
Henrik

Am 14.03.2016 um 11:11 schrieb Miroslav Lichvar:
> On Sat, Mar 12, 2016 at 08:15:48AM +0100, Henrik Bieler wrote:
>> Hey Miroslav,
>>
>> thank you for your input. This works indeed. :-)
>> When chrony has selected the GPS and the stratum 1 ntp servers come
>> online, chrony selects one of them.
>> So far I could not yet observe chrony switching back to gps when the
>> servers go offline. The servers are still shown in "chronyc sources" as
>> selected. But maybe I just need to give it more time.
> 
> A refclock using NMEA messages is usually much worse than an NTP
> server. It may take a while before the estimated error of the NTP
> sources becomes larger than the error of the refclock and chronyd
> reselects. With chrony < 2.0 you can force the reselection to happen
> sooner by not switching the NTP sources to the offline state via
> chronyc. After 8 unanswered requests they will become "unreachable"
> and will be ignored in the source selection. In chrony >= 2.0 that
> wouldn't make a difference.
> 


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