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

[<thomas.schmid@xxxxxxxxx>]

Hi Bill,
> -----Ursprüngliche Nachricht-----
> Von: Listengine [mailto:listengine@xxxxxxxxxxxxxxxxx] Im Auftrag von
> Bill Unruh
> Gesendet: Donnerstag, 8. September 2011 06:11
> An: chrony-users@xxxxxxxxxxxxxxxxxxxx
> Betreff: Re: [chrony-users] chronyd: Can' Synchronize WHY ?
> 
> 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
This is the current HEAD, 1.2.6 + all changes up to September 1. 

> > 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?
<WAN-IP1> is connected by a 7 Mbps WAN connection, 2 LAN and 1 WAN-hop away..
<WAN-IP2>: The intermediate NTP server (WinXP+Meinberg ntpd) sits in the same
LAN; however the WinXP is a virtual machine running on VMware Server 1.0.10..
Note: I know it's a big NO NO to run NTP servers out of (VMware) virtual machines,
But 1) currently I have no other option 2) it makes for a good worst case
testing.

> 
> 
> > ^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
Sorry to mislead you: Due to my somewhat unusual system, I have to set up NTP
sources which may not be available; and these 2 are such a case: Their IP address
is not reachable.

> >
> > 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.
Actually <WAN-IP1> should be a really good source, but I have attached the
statistics of PZF1 and PZF2 (as seen in the web interface), maybe it tells 
you something else.
<WAN-IP1> = Meinberg_M300_PZF1_stats_20110830-20110908.PNG
<WAN-IP2> = Meinberg_M300_PZF2_stats_20110830-20110908.PNG

> 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.
Same as above, sorry for confusing you: SU and LU are not reachable in
this particular setup. 

> > 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?
PZF1 = <WAN-IP1> is behind a LAN/WAN/LAN-connection, with the WAN connection
having 7 Mbps, going through 3 routers
PZF2 = <WAN-IP2> intermediate NTP server is in the same LAN as chrony, but 
inside a [WinXP+ntpd] virtual machine running on VMware server 1.0.10; this
again is connected by LAN and routers through a firewall to PZF2.

> > 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.)
Hm, even if I have 3 valid NTP servers (setup with a valid <WAN-IP1>,
<WAN-IP2> and "SU-Server3") I see the "can't synchronize" message a lot.

> > 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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Attachment: Meinberg_M300_PZF1_stats_20110830-20110908.PNG
Description: Meinberg_M300_PZF1_stats_20110830-20110908.PNG

Attachment: Meinberg_M300_PZF2_stats_20110830-20110908.PNG
Description: Meinberg_M300_PZF2_stats_20110830-20110908.PNG