Re: [chrony-users] chronyd: Can' Synchronize WHY ?

[Bill Unruh <unruh@xxxxxxxxxxxxxx>]

On Thu, 8 Sep 2011, thomas.schmid@xxxxxxxxx wrote:

> Hi all,
>
> I get a lot of the following chronyd messages in syslog:

What version of chrony


> Sep  8 00:50:52 Com-PC chronyd[3240]: Selected source <WAN-IP1>
> Sep  8 00:52:01 Com-PC chronyd[3240]: Can't synchronise: no majority
> Sep  8 01:02:18 Com-PC chronyd[3240]: Selected source <WAN-IP1>
> Sep  8 01:02:59 Com-PC chronyd[3240]: Can't synchronise: no majority
> Sep  8 01:03:27 Com-PC chronyd[3240]: Selected source <WAN-IP1>
> Sep  8 01:04:09 Com-PC chronyd[3240]: Can't synchronise: no majority
> Sep  8 01:04:35 Com-PC chronyd[3240]: Selected source <WAN-IP1>
> Sep  8 01:05:18 Com-PC chronyd[3240]: Can't synchronise: no majority
> ...
>
> The relevant section from chrony.conf:
> ...
> ; remote-WAN
> server <WAN-IP1> iburst prefer presend 5
> ; remote-WAN
> server <WAN-IP2> presend 5
> ; local-LAN
> server su-server1 maxpoll 7
> ; local-LAN
> server lu-server maxpoll 7
>
> chronyc> sources
> 210 Number of sources = 4
> MS Name/IP address           Stratum Poll LastRx Last sample
> ============================================================================
> ^x <WAN-IP1>                        1    6     49    +13us[ -877us] +/- 1148us
> ^x <WAN-IP2>                        2    6     46   +192ms[ +192ms] +/-   56ms

Yee gads, that's pretty horrible, except for wanIP1
IP2 seems really really far away. Why is it taking so long?


> ^x SU-Server1.<domain>       0    7    10y     +0ns[   +0ns] +/-    0ns
> ^x LU-Server.<domain>         0    7    10y     +0ns[   +0ns] +/-    0ns

Well something is certainly screwed up there. This says that the last
measurement was 10 years ago. Also while this says it is 0 ns jitter, below it
says it is 4000ms jitter. 
Something is seriously messed up here
> chronyc> sourcestats
> 210 Number of sources = 4
> Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
> ==============================================================================
> <WAN-IP1>                      5   3   275  -2495.179   7713.381    -50ms  2452us
> <WAN-IP2>                      4   3   193    568.775    561.325   +202ms  1119us
> SU-Server1.<domain>.   0   0     0      0.000   2000.000     +0ns  4000ms
> LU-Server.<domain>      0   0     0      0.000   2000.000     +0ns  4000ms

This is a complete mess. ip1 has a frequency 2000PPM out, with a horrendous
skew.

How are you connecting to the SU/LU servers?
Why do they have 0 ns offset? They also have no entries (NR NP) I can see why
chrony is completely confused and has no idea what the right time is.


> Both reachable time sources are DCF77 (Meinberg M300 PZF, Host "PZF1" and "PZF2"):
> - <WAN-IP1> is the Meinberg PZF1 itself (-> Stratum 1)
> - <WAN-IP2> is the Meinberg PZF2 run via WinXP+Meinberg NTPd package, simulating an
>  intermediate time server (-> Stratum 2)

Where are they?




> Would somebody please explain to me in "laymen's terms" why chrony cannot come to a selection ?
> Note: ntpd shows the same behaviour by switching it sys_peer also quite frequently.

You only have two servers, the WAN servers, and they disagree on what the
right time is. Chrony has no idea which one to believe, since there are only
two of them (whichis why you should have an odd number.)


> Thanks,
> Thomas Schmid

--
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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