[ntp:questions] NTP not syncing

unruh unruh at invalid.ca
Sat Nov 2 20:41:48 UTC 2013


On 2013-11-02, antonio.marcheselli at gmail.com <antonio.marcheselli at gmail.com> wrote:
>> 
>> >      server 127.127.1.0
>> 
>> >      fudge 127.127.1.0 stratum 10
>> 
>> 
>> 
>> Remove the above.  Although it seems to be ignoring them at the moment, 
>> they are nearly always wrong, and are incompatible with tos orphan.
>
> Thanks. I was suggested those parameters on another forum. The reason was that if the NTPs are not reachable it locks on itself.
>

And that accomplishes what for you?


>> 
>> >      tos orphan 4
>> 
>> 
>> 
>> Caution 4 is rather low, but that is not relevant here as you are not in 
>> orphan mode.
>
> I can change to something higher to be on the safe side.

Or remove it. YOu are not using it. 

>
>> 
>> It looks like the software clock is outside the usable range.  What's 
>> more worrying, if it sometimes works, is that it varies from time to 
>> time enough to put it just inside the useful range.
>
> Ok, then I need to ask you what exactly "frequency error" means. I've been looking everywhere and still I fail to completely understand its meaning.

The system advances the system clock by 1/100the of a second or 1/1000
of a second every x ticks of the cpu clock where x is determined on
bootup. ntpd determines if the rate of the ticks are done at 1/100 or a
second per 1/100 of a second or at some different rate. If it is a
different rate then that is a frequency error. Frequecy errors can arise
because the crystal driving the system time heats up, or ages or
whatever. 
 
>
> It's a Supermicro Server board, is it possible it's so unreliable??

Sure. No idea what a Supermicro Server board is. 

>
>> The first bit you can deal with by using the kernel time control utility 
>> (names vary) to correct the frequency in steps of 100 ppm.  However, if 
>> the frequency is not stable, that will not give you good timekeeping.
>
> Could you point me somewhere about it? I've never heard of it. What is it?

Under linux it is a program called adjtimex.

>
>> > Could someone please help? I can add a forth server if needed, I also understand that it would be recommended to use the iburst parameter.
>> 
>> Adding a Scottish server, or even a fourth one from elsewhere won't help 
>> as you already have three servers that agree with each other.
>
> eheh, I beg your pardon, I'm Italian, I mispelled it! :)
>
>> As it should have stepped before the error reached 7 seconds, it is also 
>> possible that they disabled stepping.  If the drift file value is way 
>> out, that might cause some problems in getting lock.  It will also tend 
>> to prevent use of the higher quality kernel time discipline.
>
> How can I verify if the stepping has been disabled or not? 
> ntp.drift at the moment is -500.000

Which is way out of spec and cannot be corrected by ntpd.

>
> Thanks for your help!
> Antonio



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