[time-nuts] Does GPS time reception work everywhere all ofthetime?

[Bob Camp]

Hi

Indeed, there's not much you can do to figure out which of the two is
correct. This is well explained in the NTP doc's. My concern was that people
drop back to 1 or 2 servers from 6 or 8 and hop from one issue to another. 

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Michael Conlen
Sent: Tuesday, August 31, 2010 9:46 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Does GPS time reception work everywhere all
ofthetime?

If it has one it has no choice but to accept that the one server has the
right time, if it has two it has no way to tell which is most likely to be
closest to correct. If it has three or more it can make value judgements. 

--
Mike

On Aug 31, 2010, at 9:12 AM, Bob Camp wrote:

> Hi
> 
> On the other hand, NTP gets bothered if it has only 2 independent
partners.
> It's quite happy with one, but two seems to bother it. Three or four seems
> to be a "sweet spot".
> 
> -------------------
> 
> Still beating on the email problem... seems to be a router somewhere in
Ohio
> or Illinois that's the issue. May get fixed some day, until then no
incoming
> email. 
> 
> Bob
> 
> =============
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Poul-Henning Kamp
> Sent: Tuesday, August 31, 2010 4:58 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Does GPS time reception work everywhere all of
> thetime?
> 
> In message <4C7CC2F1.3060604 at orange.fr>, mike cook writes:
> 
>> of references about how to do this in a belt and braces manner. How far 
> you go (5 independent clocks should be sufficient) depends on how much 
>> your downtime costs.
> 
> Let me just add a bit of caution here:  The NTP software gets confused
> if it has too many servers to select from.
> 
> I would _never_ advice configuring more than 5 ntp servers for any
> machine, unless some of them deliberately are made unavailable and
> only used for monitoring/sanity-check.
> 
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by
incompetence.
> 
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> 
> 
> 
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