[ntp:questions] no ntp synchronisation: 2s to 6s time shift !

Unruh unruh-spam at physics.ubc.ca
Tue Feb 12 17:23:11 UTC 2008


Thierry MARTIN <thierry-martin at ifrance.com> writes:

>Hello,

>Can anyone tell me if a time shift greater than 2s per day is ""normal"" 
>on a linux system that has no "external" synchronisation (ntp)?

Sure. In fact that is small. 2s/day is 20PPM , and I have machines which
have a 80PPM drift. Also some with a 6PPM drift. So 2s/d is certainly
within the range.


>I tryied "adjtimex -a" which gives unreliable results: it worked fine on 
>   one machine (less than 1s shift / day) and badly on another one 
>(several seconds shift / day)

>Any info about this subject would help me.

Use ntp to synchronize externally.

With no external sync, ntp and your computer has no way of knowing what the
"right" time is. And depending on the use your computer gets, fluctuations in
the drift of seconds per day are certainly possible (unusual but possible) from Temp variations
within the machine. 




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