[LEAPSECS] leap seconds in POSIX

[Brooks Harris]

On 2020-01-28 12:15 AM, Martin Burnicki wrote:
> Brooks Harris wrote:
>> Evolution of Timekeeping in Windows
>> https://techcommunity.microsoft.com/t5/networking-blog/evolution-of-timekeeping-in-windows/ba-p/778020
> Interesting that they call it "the (r)evolutionary changes to time
> keeping in the Windows operating system" when they finally managed to
> achieve a precision that other operating systems are already providing
> since decades. ;-)
>
> Martin

I hate Windows. However its the operating system I know. I certainly do 
not want to get into OS wars because the fact is we all must deal with 
all of them in one way or another, especially where timekeeping is 
concerned.

But it's a little unfair to say "Windows" cannot do tight timekeeping. 
It depends on the *version* of Windows and administrative set ups. It is 
true that the normal consumer versions default to polling NTP once a 
day, so they are not very accurate. However, it has been possible to set 
up Windows Server for high quality time services since Windows 2000. I 
was involved in an elaborate installation of Windows 2000 and Linux 
machines in the early 2000s and the timekeeping was pretty tight. It was 
not easy to accomplish because it involved all sorts of careful Registry 
tweaks to get it all to behave.

How to configure the Windows Time service against a large time offset
https://support.microsoft.com/en-us/help/884776/how-to-configure-the-windows-time-service-against-a-large-time-offset

Of course this has evolved over the years.

How the Windows Time Service Works
https://docs.microsoft.com/en-us/windows-server/networking/windows-time-service/how-the-windows-time-service-works

Windows Server is a somewhat different animal than 'consumer' and 
'professional' Windows. They do not give the Server versions away and I 
expect we can all agree that those licensing costs are exorbitant. But 
Microsoft is the Borg. Bill Gates has not been returning my calls recently.

--------------

On the recent leap-seconds support now enabled in Windows:

Leap Seconds for the IT Pro: What you need to know
https://techcommunity.microsoft.com/t5/networking-blog/leap-seconds-for-the-it-pro-what-you-need-to-know/ba-p/339811

Leap Seconds for the AppDev: What you should know
https://techcommunity.microsoft.com/t5/networking-blog/leap-seconds-for-the-appdev-what-you-should-know/ba-p/339813

I think this is going to cause more problems than it solves when the 
next leap-second comes around. Yes, supporting the leap-second directly 
seems a good thing to a point. (Note there are important administrative 
setups involved to enable this support on various Windows versions.) 
However, systems so enabled will produce timestamps that are inaccurate 
with respect to classic Windows and POSIX timestamps. Their objective is 
to claim traceability to UTC, especially in context of Azure cloud 
services, and that it will be. However, after the next leap-second those 
timestamps will be one second off from every other system on the planet 
and incompatible with the vast majority of applications including most 
Microsoft applications, like Office. Will they actually update Office 
timekeeping to match? BackOffice? SQL Server? .NET? What then of legacy 
timestamps and applications? How difficult will it be to compare Windows 
timestamps to Linux timestamps? Or HTML, XML, email, etc, etc. It looks 
to me this is going to cause some serious practical incompatibility 
issues. I'm not seeing how this will make things easier.

-Brooks