On Mon, Sep 05, 2016 at 02:55:13PM +0200, Leo Baltus wrote:
> > > $ chrony sources
> > > 210 Number of sources = 3
> > > MS Name/IP address         Stratum Poll Reach LastRx Last sample
> > > ===============================================================================
> > > ^- ntp1.omroep.nl                3   7   377    96   -919us[ -919us] +/-  
> > >  26ms
> > > ^- ntp2.omroep.nl                3   6   377    55    -67us[  -67us] +/- 
> > > 9384us
> > > ^- ntp3.omroep.nl                3   9   377   996    +36us[  +31us] +/- 
> > > 6541us
> > > 
> > > So there apears to be no currently selected source. Moments later Chrony
> > > selects a source and 'chrony sources' shows lines beginning with ^+ en ^* 
> > > again.
> > > 
> > > Can I assume that this is normal bahaviour? And should minotoring
> > > scripts assume both 'states' are ok? i.e. interpret lines begining with 
> > > ^- ^* ^+
> > > as 'chrony-is-happy'?

> In a normal situation chrony changes sources from time to time.
> Before synchronizing to a new source, is it entering the 'state' as
> described above?

Yes, there is a state in which chronyd is waiting with the source
selection for more updates. It's completely normal to see all sources
with the - flag. It can happen when a new measurement of the currently
selected source makes it worse than the other sources. A source can be
selected only when it has a new measurement. So, if the new
measurement made it the best source, it can be selected immediately,
but if the measurement made it worse, another source needs to get a
new measurement before it can be selected. 

> As this is a transient state should monitoring report about it? If
> not, what should be reported as a faulty state?
> 
> My guess is:
> if all sources report *+ or -, chrony is ok
> if all sources report neither *+ or - chrony is not ok

It depends on what exactly you want to be monitoring. If individual
time sources, checking for the *, +, - flags is a good idea. If some
source has x (falseticker) or ? (unreachable), it doesn't mean chrony
is not ok, other sources can still be good enough. If you are more
interested in monitoring if and how the system clock is synchronized,
it's better to check the values from the tracking report. The Leap
status should not be "Not synchronised" and the root dispersion plus
half of the delay should be smaller than the maximum error of the
system clock you find acceptable.

-- 
Miroslav Lichvar

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