On 2012-12-09 17:00, David Taylor wrote:
On 09/12/2012 15:00, Jeroen Mostert wrote:
It is a shame that nothing *outside* the reference documentation (in
particular quick-start guides) seems to describe the use of this option,
though. It's also unfortunate that ntpd has been around so long (with
relatively few changes) that outdated documentation is a dime a dozen.
Nothing describes "pool"? Well, my Windows set-up page (also referenced by
Meinberg) does for a start.
Yes indeed: "David Taylor created a detailed step-by-step walkthrough of the
installation on his website."
Pshaw! As if I'm going to read some step-by-step walkthrough! There's
screenshots below the thing, right? This David Taylor guy can't possibly have
something more interesting to say.
The above is, of course, steeped in irony, since your site is a veritable
treasure trove for people setting up NTP under Windows. I really wish I'd
stumbled across it sooner. I know I didn't find it through the Meinberg site.
As I mentioned, I haven't tried Internet servers alone recently on Windows
except for one brief test with Windows-8 (because it has more precise time
routines):
http://www.satsignal.eu/ntp/Win-8+Internet.html
and I did a test with a Linux server, WAN-only as well:
http://www.satsignal.eu/ntp/2012-11-10-11-12-raspi1_ntp-b-day.png
If precise timekeeping is important, it may be worth upgrading to Windows-8
(although I saw an improvement on only one of two PCs tested).
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.
It may well be that 30 - 40 ms is the best you can expect without some local
server (e.g. FreeBSD/Linux/Win-8 box on your LAN), but stepping every hour
should not normally be happening.
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.
--
J.
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