Re: [chrony-users] High skew values

[Bill Unruh <unruh@xxxxxxxxxxxxxx>]

On Wed, 24 Jul 2013, Arnon Weinberg wrote:

> chrony is not setting the time.
>
> /var/log/messages contains many of the following type of entries:
> chronyd[490]: System clock wrong by 15.124741 seconds, adjustment started
> chronyd[490]: Can't synchronise: no majority
>
> Additionally, chronyc -> sourcestats shows very high skew:
>
> chronyc>  sourcestats
> 210 Number of sources = 4
> Name/IP Address            NP  NR  Span  Frequency  Freq Skew Offset  Std Dev
> ==============================================================================
> S0106bcaec5c4f690.vc.shaw   4   3     7 -68474.500     479381 -119.5s    84ms
> zeit.rcloran.net            4   3     7 -58189.289     471160 -101.5s    59ms
> ox.eicat.ca                 4   3     6 -81081.703     354399 -141.5s    48ms
> mirror.mountaincable.net    4   3     7 -49499.297     381278 -86.3s    46ms

Well, it is not surprizing that chrony can do nothing. The sources disagree
violently with each other. It is saying that the offsets from the various
sources disagree by 22 sec--- way way way higher than chrony can do anything
with, and the frequency of the sources disagree by 30000 which again is
absurd.
Are you running chrony on a virtual machine? Note that MR is 3 in each case
which says that the individual points are completely incoherent which the freq
and offset already say.

It may be that your machine is very sick (eg a virtual machine) or that
something else is changing the time randomly on your system.


> I interpret this to indicate very high network latency, but the network is 
> fine:
> > ping zeit.rcloran.net
> --- zeit.rcloran.net ping statistics ---
> 5 packets transmitted, 5 received, 0% packet loss, time 4021ms
> rtt min/avg/max/mdev = 0.386/19.406/26.854/9.787 ms
> > ping ox.eicat.ca
> --- ox.eicat.ca ping statistics ---
> 5 packets transmitted, 5 received, 0% packet loss, time 4058ms
> rtt min/avg/max/mdev = 0.314/1.326/1.777/0.568 ms
> > ping mirror.mountaincable.net
> --- mirror.mountaincable.net ping statistics ---
> 5 packets transmitted, 5 received, 0% packet loss, time 4021ms
> rtt min/avg/max/mdev = 3.527/3.763/4.032/0.174 ms
>
> So stumped now.  Why might the skew be so high?
>
>
> > chronyc -v
> chronyc (chrony) version 1.27-pre1
> > uname -r
> 3.9.10-100.fc17.x86_64

--
William G. Unruh   |  Canadian Institute for|     Tel: +1(604)822-3273
Physics&Astronomy  |     Advanced Research  |     Fax: +1(604)822-5324
UBC, Vancouver,BC  |   Program in Cosmology |     unruh@xxxxxxxxxxxxxx
Canada V6T 1Z1     |      and Gravity       |  www.theory.physics.ubc.ca/

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