Best practices question

Paul Theodoropoulos paul at
Wed Jun 26 06:37:20 UTC 2019

On 6/25/2019 23:07 PM, Hal Murray wrote:
> Most likely, that's the temperature change on the crystal. In some 
> sense, if
> that is a significant problem, that means you have a reasonably good setup.
> If you want another rathole to go down, measure the temperature of the crystal
> and plot NTP's drift vs temperature.
> You want something that reads to a small fraction of a degree.  I don't know
> of a great setup to recommend.  The standard CPU or disk temperature reading
> is usually only good to 1C.  That's great for monitoring CPU/disk temperature,
> but not good enough for making great plots.
> You don't need accuracy as long as it is consistent and reasonably linear.

Right - I have that all graphed, at the URLs I included in my original 
message. It is definitely well-correlated with temps. Naturally my graphs 
look rather sketchy right now due to all the fresh tinkering...

And I do think my overall setup is squeezing out about the best one can 
hope to get from homebuilt, short of a rubidium CSAC!

>> So I can run NTPsec without GPSD? For some reason I thought it was  required
>> to interpret the PPS from the GPS. I'll do some further reading.
>> Interesting.
> Eric and Gary came from GPSD.  They think it is the solution to all problems.
> My background is ntp-classic.  I try to avoid GPSD.  It's different.
> Sometimes better, sometimes not, sometimes just different.
Heh. Well, my experiment without gpsd (followup posted a few minutes after 
your message) wasn't particularly successful, but I would need to do a 
deeper dive into all of it before declaring it a hard failure. Too much 
room for my klutziness to be a factor.
> I forgot to mention...
> Another variable to play with is the polling interval - minpoll/maxpoll.  This
> isn't simple.  You want to see what it does in both the calm/stable "normal"
> conditions as well as how well it works when interesting things happen.
At least for each stratum 0 device, I have minpoll/maxpoll both at zero, 
as recommended....well, somewhere, and it was an authoritative source, but 
it escapes me at the moment. For the local peers on the lan, I have 
minpoll/maxpoll 3/6, and for the few 'outside' peers, I maintain 6/10, 
unless different values are requested by a peer.

The 3/6 I decided upon based on ...guessing. I should definitely poke at 
those as well.

Thank Hal!

Paul Theodoropoulos

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