[Nagiosplug-devel] check_ntp misunderstandings?

[Thomas Guyot-Sionnest]

I think a better way of solving this is to have a redudant setup with local
clocks.

Set up two of your servers as stratum 2 and add a local clock to them. Then
all other servers get their time from the stratum 2 servers.

If one server die, you'll still get time from the other. If your stratum 2
servers loose conectivity with their peers, they'll still be a valid time
source for the others servers since they'll get their time from the local
clock.

If you don't setup local clocks and loose conectivity with all external
sources your time servers will be useless. You can setup a local clock with
the following lines in ntp.conf:

server 127.127.1.0
fudge 127.127.1.0 stratum 10

If you don't care about time sync between hosts you could also set-up local
clocks on individual servers. Fudge with a stratum at least two levels over
their peer's local clock (Stratum 12 for the example above)

Thomas

> -----Original Message-----
> From: nagiosplug-devel-bounces at lists.sourceforge.net 
> [mailto:nagiosplug-devel-bounces at lists.sourceforge.net] On 
> Behalf Of Gerhard Lausser
> Sent: July 27, 2006 13:39
> To: nagiosplug-devel at lists.sourceforge.net
> Subject: [Nagiosplug-devel] check_ntp misunderstandings?
> 
> Hi,
> 
> i have a problem understanding what check_ntp actually 
> checks. Let's say, i
> have a time service infrastructure like this:
> 
> lantime1.dom                     # stratum 2
> (xntpd)
>   |   \ 
>   |     \
>   |       \
> ntp1.dom   ntp2.dom              # stratum 3
> (xntpd)    (xntpd)
>   |        /
>   |      /
>   |    /
> srv1.dom                         # the server i monitor with 
> nagios     
> (xntpd)
> 
> 
> srv1.dom has a ntp.conf containing
> server ntp1.dom
> server ntp2.dom
> 
> If i understand check_ntp right, i would execute "check_ntp 
> -H ntp1.dom"
> on server srv1.dom.
> Now this will result in two calls:
> 
> 1) ntpdate -q ntp1.dom
> which will show me a difference of the clocks of my server 
> srv1.dom and its
> master ntp1.dom. This is so far what i expected.
> 
> 2) ntpq -np ntp1.dom
> which will show me information on the synchronization of the clocks of
> timeserver ntp1.dom and its master lantime1.dom. I am actually not
> interested in this and i dont want to be alerted if 
> lantime1.dom does no
> longer exist or has other difficulties.
> What i would call here is ntpq -np 127.0.0.1 and query the 
> local xntpd which
> gives me further details about synchronization of my 
> monitored host and it's
> master.
> 
> So as i see it, check_ntp checks two different relations between three
> clocks, while i am only interested in one relation between two clocks.
> 
> Am i the only one who is confused?
> 
> Greetings from Munich,
> Gerhard
> 
> 
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