[ntp:questions] Can anyone interpret these loopstats?

David J Taylor david-taylor at blueyonder.not-this-bit.nor-this-bit.co.uk
Fri Nov 23 22:45:49 UTC 2007

Richard B. Gilbert wrote:
> David J Taylor wrote:
>> Folks,
>> I've been monitoring my Windows Vista system using the Meinberg
>> distribution NTP, and it seems to have a peculiar behaviour of
>> alternate good and bad timekeeping:
>>   http://www.david-taylor.myby.co.uk/mrtg/gemini_ntp.html
>> Can anyone who understands loopstats and peerstats better than I do
>> explain what's going on.  The files are here:
>>   http://www.david-taylor.myby.co.uk/gemini-vista-stats.zip
>> In the event log NTP is showing errors: "Unable to initialise the
>> .rnd file", but I don't think that's key to the operation of NTP
>> itself.  The NTP service shows as running, and the W32time service
>> as stopped. Thanks,
>> Puzzled from Edinburgh (a.k.a. David)
> How about your ntp.conf?  What does your ntpq -p banner look like?
> I would make a small bet that the network between you and your
> upstream servers is a real mess but looking only at your graphs
> doesn't tell me much more than that.

Richard, thanks for that, but the network is very clean.  The upstream 
server is a GPS-synced device, and the performance can be seen before the 
Vista upgrade at the end of week 45.  Very flat.  The ntpd.conf is 
essentially unaltered, and whnever I check the banner shows the PC as 
synced to the GPS stratum one server.

> I'm rather puzzled by the timing of the relatively flat period on your
> daily graph.  It seems that you are getting the best performance
> between about 11 AM and 9:30 PM.  I would expect the network to be
> busiest during that period and consequently I would expect to see the
> worst performance during that period.

Yes, I don't think it's network related at all.  To me, it seems almost 
that there are two sync sources at work, and I'm seeing the beat between 
them.  But, no, the W32time service is stopped.  It puzzled me, so I 
asked.  You can see the network load into that PC here:


Normally, very light.  The software tasks now running under Vista are 
basically the same as those running under XP before, and the same versions 
of the software.

> What happened on Friday of week 45?  It looks as if that was about the
> time everything turned to worms!

That was when the PC had Vista installed (fresh, not upgrade).  I was 
hoping that Heiko might look at this, as he reported "good" performance 
with Vista much earlier this year.


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