[ntp:questions] Re: Getting good NTP tracking
Richard B. Gilbert
rgilbert88 at comcast.net
Mon Jun 26 21:40:59 UTC 2006
Eino-Ville Talvala wrote:
> Richard B. Gilbert wrote:
>
>> Eino-Ville Talvala wrote:
>>
>>> Ok,
>>>
>>> I've been messing with this for a few weeks, and haven't yet managed
>>> to get NTP to where I'd like to be (and where I think it should be
>>> able to be).
>>>
<snip>
>>> <UNIVERSITY> 84 -2.083 115.705 931.227 7.427 46.999
>>> 14.830
>>> <DEPARTMENT> 84 4.506 7.546 41.621 2.652 39.808
>>> 14.828
>>> <SECOND MACHINE> 85 1.590 3.878 14.613 1.384 32.507
>>> 18.043
>>>
>>> ----------------------------------------------------
>>> And here's the driftfile:
>>>
>>> -96.459
>>
>>
>> I'm a little puzzled by the low values of "cnt". With 84-85 samples
>> per day, it looks as if your system is polling the servers at the
>> maximum poll interval of 1024 seconds. Did you, by any chance, tamper
>> with the default values of MINPOLL and MAXPOLL? It's generally a poor
>> idea. Ntpd will adjust the poll interval upwards and downwards as
>> conditions change and as limited by MINPOLL and MAXPOLL. The defaults
>> allow for the conditions usually found. By setting MINPOLL to 10, you
>> force the longer polling interval even when ntpd needs a shorter
>> interval to achieve good synchronization!
>>
>
> I've certainly not intentionally changed it anywhere - if that's an
> ntp.conf setting, I haven't changed it.
>
> I should clarify a bit - I just added the 3 public pool servers and
> turned off SELinux protection for ntpd this morning, so I don't yet know
> if those changes may fix my problem.
Look at your /etc/ntp.conf. In that file, look at the server
statements. Do they include the keyword MINPOLL? Or MAXPOLL?
I suspect that you have server statements that look like this:
server ntp1.abc.org minpoll 1024
If you find minpoll and/or maxpoll keywords, remove them and their
associated values and restart ntpd. It might be a good idea to make a
backup copy of the ntp.conf file before changing it.
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