[ntp:questions] Win7: ntpd adjusting time backwards

David Taylor david-taylor at blueyonder.co.uk.invalid
Sun Dec 9 17:18:17 UTC 2012

On 09/12/2012 16:26, Jeroen Mostert wrote:
> As long as Microsoft still doesn't make it possible to upgrade the
> kernel without upgrading the shell, that's not going to happen, because
> the Windows 8 UI is a serious productivity killer for me.
> The broader context is that I'm working on an NTP setup for a "real"
> network, where the only demand is that the servers stay within each
> other's times to some reasonable degree (I'll take anything <= 10 ms),
> with only very lax demands on synchronizing to absolute time. I've
> already discovered that this is actually fairly easy as long as all
> machines sync to a single local server with some frequency (setting
> minpoll 4 maxpoll 4 is no problem on a LAN, of course, and keeps even
> the most wayward machines in line). I'm still happy I ran into problems
> locally, because upgrading to 4.2.7 significantly reduces jitter even in
> this setup (as reported by your site as well), so I'll be sure to
> slipstream that in.
> Of course, upgrading all machines to Windows 8/Windows Server 2012 just
> to get better time synchronization isn't going to happen. :-)
> For now the local server is a Windows Server 2008 machine, but I've
> already petitioned for a dedicated Linux machine (FreeBSD would be too
> "out there" for IT, I'm afraid...) If possible, we can later upgrade
> that to something with a GPS, but it's probably not necessary at the
> moment.
> If 30-40 ms is realistic for syncing to internet time, I'll take it.
> Though it's slightly disappointing, but I guess the limitation is in
> Windows more than it is in NTP.

Win-8 is almost the same as Win-7, just add a start-menu add-on such as 
ClassicShell.  Quite tolerable, then (although DOS shell, run as 
Administrator takes a little more effort!).

What I would agree for your situation is to have a local server to which 
you tight-lock (low min/maxpoll) the rest.  But as a result of my own 
recent tests, I would make that local server a Raspberry Pi or similar 
(it's very low cost) running Linux and synced to the Internet, and if it 
suits, make that a stratum-1 server with a GPS/PPS for a score of 
dollar/pounds more.

No need to upgrade all PCs, just one server.  PCs Hydra and Narvik here 
are on a LAN connection.


and PCs Molde, Puffin, Torvik and Ystad are Wi-Fi connected (which 
doesn't help timekeeping).  Note the difference between XP and Windows-7.

Your suggested arrangement of a Linux time server (which can be a very 
simple, low-powered PC) and tight coupling of the rest should give you 
excellent results.
Web: http://www.satsignal.eu

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