[ntp:questions] NTP not syncing

unruh unruh at invalid.ca
Mon Nov 4 21:14:09 UTC 2013


On 2013-11-04, Charles Swiger <cswiger at mac.com> wrote:
> Hi--
>
> On Nov 4, 2013, at 9:40 AM, Antonio Marcheselli <puppa at me.la> wrote:
>> Would it be wiser to delete the drift file at boot - by script - and let ntpd resync and recreate a new drift file?
>
> Normally, no.
>
> The drift file lets ntpd perform a first-order correction of the average intrinsic drift of the local clock even if ntpd can't get time from any other sources.  However, if the drift can't be computed correctly because of some unusual problem-- and a systemic drift of over 500ppm is fairly unusual-- then deleting the drift file might help.

It used to be on older version of linux, that the calibration of the
computer clock on boot was off. Thus the calibration would mean that the
clock rate would vary by 50-100PPM on successive reboots. This would
make the drift file pretty useless. 
>
>> As mentioned, I don't really need my system to be synced down to the millisecond, if ntpd takes a few hours to settle and the time is off up to a few seconds during that time it's perfectly fine with me.
>
> Gracious.  In that case, run ntpdate via cron every hour or so and you'll probably stay within that tolerance even if ntpd itself can't manage to stay in sync.  However, if switching your system's clock source from whatever you are using now to HPET, ACPI, etc improves matters so that ntpd remains stable, that would obviously provide much better timekeeping.
>
> Regards,



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