[LEAPSECS] Windows Server 2019

Martin Burnicki martin.burnicki at meinberg.de
Thu Jul 19 03:45:14 EDT 2018

Steve Allen wrote:
> On Thu 2018-07-19T04:14:12+0100 Stephen Colebourne hath writ:
>> "In addition, there is no standard method for applying this frequency
>> adjustment, so that different implementations may disagree among
>> themselves in addition to the time error with respect to UTC."
> That quote is not from Microsoft, but rather from the
> ION paper by Matsakis, Levine, and Lombardi
> That can be got by ION members, or from USNO if their
> webserver recovers, or from researchgate if you can
> tolerate the javascript that will try to execute
> https://www.researchgate.net/publication/323600621_Metrological_and_legal_traceability_of_time_signals

Thanks for the pointers.

> Microsoft seems to be documenting a new mode of OS configuration which
> actually does count the second named "60", and specifically in order
> that Microsoft systems can say they conform to MiFID II and other
> regulatory agencies that demand conformance with UTC as defined.
> Otherwise the old default configuration will have a second that lasts
> 2000 millis.

I wonder what you mean by "old configuration". The latest leap second
tests I made with Windows and w32time running showed that there was no
leap second handling at all.

This means whenever w32time polled an NTP server the next time after a
leap second (which could be up to 1 week, with a 1 week polling interval
for machines that are not members oof an Active Directory)) it simply
observed a time offset > 1 s, and adjusted the Windows time accordingly.

Slewing the Windows system time over 2 seconds is a feature of the ntpd
port for Windows (and the Meinberg time adjustment service for their PCI
cards), which implements this slewing as a workaround for windows.

If Windows starts to provide an API to handle leap seconds then these
programs should use the API, if it is available, and skip the workaround.

Martin Burnicki

Senior Software Engineer

MEINBERG Funkuhren GmbH & Co. KG
Email: martin.burnicki at meinberg.de
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