[ntp:questions] Automatic time synchronization of local hw clock.

Martin Burnicki martin.burnicki at meinberg.de
Tue Apr 22 09:37:46 UTC 2014

David Taylor schrieb:
> On 14/04/2014 10:33, David Woolley wrote:
> []
>> This is something that is done by the operating system (e.g. every 11
>> minutes in Linux, or by cron jobs in some other systems), not by ntpd.
>> Some people object to this behaviour in Linux because it prevents the
>> effective use of hwtime to correct RTC frequency.
>> As such, the identity of the OS is important in answering the question.
> I must admit I would like to see NTP doing this in Windows more often
> than it does.  At the moment, as I understand it, the RTC is only
> updated by NTP on a Windows Shutdown event, not when NTP is restarted.
> and not on a regular basis such as every 10 minutes.  Obviously, the RTC
> should only be updated if NTP is confident that it's at the correct
> time....!

AFAIK there is no way to do this in Windows reliably without messing up 
the normal timekeeping done by ntpd.

There might be possible hacks using undocumented calls which would 
probably result in new potential problems. See also my other post.

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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