[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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