[ntp:questions] Client using Meinberg NTP can't sync with ntp server problem
martin.burnicki at meinberg.de
Fri Jul 11 08:46:15 UTC 2014
vothanhhung22 at gmail.com wrote:
> Hi all,
> I read and followed as the link Martin suggest and I tried to find the latest version. Can you check for me if this link is the latest because I tried this link but it is not working. I tried set minpool to 9 but it doesn't work.
In the message to which I've provided a link I tried to explain that
(and why) polling intervals below 6 and above 7 may not yield proper
results. So why don't you try this?
server 0.hk.pool.ntp.org minpoll 9 maxpoll 11 iburst
server 0.hk.pool.ntp.org iburst minpoll 6 maxpoll 7
> Here is the link: http://www.satsignal.eu/ntp/x86/ntp-4.2.7p447-win-x86-bin-djt.zip
Strange. This download link works fine for me. Can you access
That's the web page which provides that link.
> In my case (as William explained) it is not a normal clock rate sync but just a copy time from ntp server to machine clock.
What do you mean by: "not a normal clock rate sync but just a copy time"
> So what I am wondering now is if it is right in my situation to use ntp to "sync" from ntp server.
> The machine I am trying to "sync" is a VPS machine.
Do you mean your Windows system runs inside a Virtual Machine (VM)?
Even in physical machines is usually pretty tricky to synchronize the
Windows system time accurately. In VMs it's even harder since the
virtualization usually also causes more or less additional jitter,
depending on how much effort the vendor of the virtualization software
has spent for timekeeping inside the VMs.
So the resulting accuracy you can yield with NTP in a VM may be better
or worse, depending on which virtualization software you are using
(VMWare? MS Hyper V?), but is usually always worse than with the same OS
running directly on a physical machine.
If this is sufficient, or not, depends on the accuracy you need or expect.
> I still don't get the point William explained that "you cannot "force it to sync every 10 min" that is not how it works". Can you explain me more?
Real NTP (ntpd) gets the time from a server in periodic polling
intervals. The results from several pollings are filtered, and the
filter output is used to slew the system time slowly and continuously so
that there are no time steps in the system time and the system time
doesn't drift away from "real" time.
Usually the polling interval is adjusted automatically by ntpd in the
range 2^6 (=64) to 2^10 (=1024) seconds. However, under Windows polling
intervals above 2^7 don't yield good results, so you should limit
maxpoll to 6 or 7.
Forcing it to synchronize every 10 minutes might mean you run a tool
every 10 minutes to get the current time and then set the Windows system
time, which yields much worse results than you can achieve with NTP.
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