[ntp:questions] Increase maximum frequency offset to deal with really bad clock
Richard B. Gilbert
rgilbert88 at comcast.net
Wed Jan 28 22:19:57 UTC 2009
jeff at sailorfej.net wrote:
> Hi folks,
>
> I have a some FreeBSD systems running as guests in Microsoft Virtual
> Server. There is a known problem with these were the clocks run very
> fast. I am trying to use ntpd to keep their clocks in sync, but the
> frequency error offset is exceeding (I think) ntpd's maximum of 500,
> my driftfile always contains a value of "-500.000". If understand the
> way this works correctly, if I could get the frequency error offset to
> represent the real error rate which I believe to be much higher that
> 500 PPM, then ntpd would be able to keep the clocks in sync, as it is
> now, it slowly falls behind until it fails to correct altogether.
>
> So is it possible to override the maximum offset PPM in the driftfile,
> or is there a better way to fix this?
>
> Thanks,
> Jeff
I'm not familiar with BSD but if there is a way to reduce the speed at
which the clock ticks, using it MIGHT bring the clock close enough that
NTPD could discipline it. The 500 PPM limits translate to +/- 43
seconds per day so, if your clock is outside the limits it is REALLY
off. The cheapest wrist watches do better than that!!
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