How is ntpd data used -

Bob Goodwin bobgoodwin at att.net
Sat Nov 6 17:34:07 UTC 2004


Rodolfo J. Paiz wrote:

>On Sat, 2004-11-06 at 08:12 -0500, Bob Goodwin wrote:
>  
>
>>Markku Kolkka wrote:
>>
>>    
>>
>>>You should insert a few minutes of delay between those two calls 
>>>to let the ntp daemon to work. 
>>> 
>>>
>>>      
>>>
>>Yes I do that -
>>
>>~  cat ./tsync
>>
>>service ntpd restart
>>
>>sleep 5
>>
>>ntpq -p
>>
>>    
>>
>
>Note Markku said "minutes", not 5 seconds. Since ntpd wants very high
>precision, it does not make abrupt changes to a system. IMHO, you should
>wait at least 15 *minutes* for ntpd to begin settling down before you
>query it.
>
>Cheers,
>
>  
>
Yes I noticed what he said but interpreted "a few minutes" as "wait a 
moment."

I found that it's necessary to wait a short time, 5 seconds works for 
me, or
else ntpq does not have time to collect the data and returns an empty
table as in the trial below :

~  ./tsyncx
Shutting down ntpd:                                        [  OK  ]
ntpd: Synchronizing with time server:                      [  OK  ]
Starting ntpd:                                             [  OK  ]
     remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
 ntp-1.cns.vt.ed .INIT.          16 u    -   64    0    0.000    0.000 
4000.00
 ntp-4.cns.vt.ed .INIT.          16 u    -   64    0    0.000    0.000 
4000.00
 ntp2.jrc.us     .INIT.          16 u    -   64    0    0.000    0.000 
4000.00
 ntp1.jrc.us     .INIT.          16 u    -   64    0    0.000    0.000 
4000.00

Initially I needed ntpq as assurance that things were working. I now have
confidence in it and will try a longer period, perhaps 1000 seconds?

However, even with the 5 seconds I believe it's correcting the clock? Or
does running ntpq upset things somehow? Result in less than optimum
correction?

Thanks for the advice.

Bob Goodwin




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