[ntp:questions] Ntp not syncing after powerfail of server

M. Giertzsch mgiertzsch at mobotix.com
Thu May 19 15:52:02 UTC 2011


Am 19.05.2011 16:01, schrieb Heiko Gerstung:
> Hi,
>
> Am 18.05.2011 11:57, schrieb M. Giertzsch:
>    
>> Hello together,
>>
>> I want to synchronise a local network and there is no uplink to the outside world.
>> So I have one dedicated ntp server and all other devices are client of this server.
>> Now if there is a powerfail, there is no guarantee that the server has finished the boot
>> before the clients have. In this case the time will not be synced.
>>
>> Is anybody aware of options taking account to this? Does anyone know threads
>> or howtos for further reading? Am I doing a mistake or do I have my clients missconfigured?
>>
>>      
> Maybe I am missing something, but if you use ntpd on the client machines, they will poll the server in intervals. So even if
> they do not get a response the first time they ask, they should receive the time on the second try (and all consecutive calls).
>
> We have no chance to tell you whether you have misconfigured your clients, because we do not know
> - what OS your clients are running on
> - what kind of NTP software you are using (ntpd version X or something else?) on the clients and on the server
> - how your current configuration looks like (ntp.conf?)
>
> I could imagine that your clients probably use ntpdate or a similar software to query the time once during startup, but that
> is just me guessing your setup. If that would be the case, all you could probably do is inserting a sleep before the ntpdate
> call or some other ugly workaround like this.
>
> Regards,
>   Heiko
>
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>    

Hello Heiko,

thanks for your help. You are totally right, I have forgotton to give 
you all these informations required.
The NTP software in use is ntpd 4.2.0a on both client and server. Well, 
I can't tell you exactly the OS in use,
but it's a linux like OS running on an embedded arm device.

The NTP configuration looks like follows:

restrict default notrap nomodify nopeer noquery
restrict 127.0.0.1
driftfile /var/status/ntp.drift
pidfile /var/run/ntpd.pid
server 0.de.pool.ntp.org iburst
server 1.de.pool.ntp.org iburst
server 2.de.pool.ntp.org iburst
server 127.127.1.1
fudge 127.127.1.1 stratum 13


May it be that iburst is the problem? Client gives up because of too 
many non-responses, or will iburst
ignore these and send another bunch a little later?

If you need any more information please ask me.
Thank you in anticipation.

-- 
Best regards,
    M. Giertzsch




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