[ntp:questions] Meinberg NTP monitor, silly question
snews at lordynet.org
Tue Dec 22 21:34:46 UTC 2009
Richard B. Gilbert wrote:
> unruh wrote:
>> On 2009-12-22, Richard B. Gilbert <rgilbert88 at comcast.net> wrote:
>>> David J Taylor wrote:
>>>> "Richard B. Gilbert" <> wrote in message
>>>> news:ZJydnVuvufm1Wa3WnZ2dnUVZ_h2dnZ2d at giganews.com...
>>>>>> You will find that for the best performance, the NTP PC needs to
>>>>>> be left running, as initial settling is not quick.
>>>>> "Not quick" is an extreme understatement! It takes about 30
>>>>> minutes to get a "reasonable approximation". It can take ten to
>>>>> twelve hours to stabilize with the best possible approximation of
>>>>> the time. Once there it's good for as long as you can keep the
>>>>> power on and the temperature reasonably stable.
>>>> On one LAN-synced system it took bout 90 minutes to get to within
>>>> its normal offset range, and about the same on a Windows-XP system
>>>> with a GPS reference clock. On the Windows-7 system, with a GPS
>>>> ref-clock, it took about 5 hours.
>>>> I do wish there were some way of speeding this up - a variable loop
>>>> bandwidth or something like that.
>>> Lots of luck. My understanding is that it can't be done without loss
>>> of accuracy and/or stability.
>> Nonsense. chrony does it, without loss of accuracy (chrony is about 3
>> times as accurate as ntp is) or stability. It will correct a few hundred
>> second initial error in far less time than ntp takes for a .01 sec error,
>> and without stepping.
> Then why don't you use chrony and stop bugging us? If it can replace
> NTPD under most common scenarios for normal and emergency operation and
> do a better job, I'm sure that it will eventually replace NTPD. Does
> anyone see that happening yet?
Yes, I've used chronyd along with ntpd for a while. I've moved
desktops and notebooks to chronyd.
What chronyd seems not to provide is peering ability with ntpd
(or it may be I've never been able to get it working), and up
to recently lacked any refclock support.
For ntpd I've had problems with long periods to come into sync,
temperature, system load or network disturbance causing
instability. With older systems it was possible to reduce these
effects by fiddling system clock frequency to within 10ppm or
so, but with most recent software some systems where previously
I had ntpd tamed are now back to being unstable due to self
calibration putting them 50ppm or more out, but not consistent
between reboots, (that isn't due to ntpd, just that it
exacerbates the problems and I suspect this will also affect
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