[ntp:questions] Odd (mis)behavior when reference clock fails

Unruh unruh-spam at physics.ubc.ca
Thu Sep 18 23:25:33 UTC 2008


hundoj at comcast.net (Rob Neal) writes:

>On Tue, 16 Sep 2008, Kevin Oberman wrote:

>> We have a fairly large "mesh" of NTP servers spread across the
>> US. Almost all have PPS reference clocks and are quite
>> accurate. Recently one of the reference clocks located across the county
>> seems to have failed. Such is life.
>>
>> The problem is that the system's time started drifting and eventually
>> became far enough out of sync with the mesh to be marked as a bad
>> ticker.
>>
>> The only way I could get the clock to slew or step the time was to edit
>> the configuration and comment out the reference clock and PPS. It looks
>> like the system will only use the time from a reference clock when and if
>> the clock is configured, even if it can't be read.
>>
>> Is there any way to "fix" this?

> 	What is it that you consider broken? Please clarify.
> 	I've re-read this several times, and don't see the problem.
> 	A reference clock broke. It was disregarded because it chimed
> 	badly.
> 	You expected something different?

A hardware clock broke. The computer which was using that hardware clock
insisted on using that hardware clock even though it gave no time. It acted
as a server, and eventually its time drifted so badly everyone else saw it
as a bad chimer. 
It seems to have had other server lines in the /etc/ntp.conf, but ignored
them in favour of a non-working refclock. 

That is how I interpret what he said, but I may be wrong as well.


> 	A clock must be configured to be used, yes. Sad but true.




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