[ntp:questions] Local clock - sync issue
David Lord
snews at lordynet.org
Thu Nov 4 01:46:35 UTC 2010
Stephen Vaughan wrote:
> Hi Kevin,
>
> I'm not sure why we have it in there, as you say it might have been part of the default config in Redhat's EL ntp package. And yep, I don't understand why it's reverting to the LOCAL clock and then just deciding to stick with it until we restart ntp.
>
Until about a year ago I had always included the lines in
my ntp.conf. I've never noticed any resulting disasters.
server 127.127.1.0
fudge 127.127.1.0 stratum 10
Since update to 4.2.6p2 I've changed to using tos orphan.
What happens without the lines for local clock?
Did you use ntpdate or ntpq -g -q to set the clock before
starting ntpd?
What is the frequency?
I've found that bad things happen at much above 50ppm.
Just now the seven systems here have:
1 2 3 4 5 6 7
offset(us) 92 715 3 51 53 399 525
frequency(ppm) 0.8 -48.5 -36.2 -18.2 -10.4 9.6 0.4
Offsets vary a lot (maybe +/- 500u) except (3) which is
from GPS but frequency usually varies less than 1ppm
David
> Cheers,
> Stephen
>
>
> -----Original Message-----
> From: Kevin Oberman [mailto:oberman at es.net]
> Sent: Thursday, November 04, 2010 6:00 AM
> To: Stephen Vaughan
> Cc: questions at lists.ntp.org
> Subject: Re: Local clock - sync issue
>
>> From: Stephen Vaughan <Stephen.Vaughan at blackboard.com>
>> Date: Tue, 2 Nov 2010 23:13:47 -0700
>> Sender: questions-bounces+oberman=es.net at lists.ntp.org
>>
>> Hi,
>>
>> We're having an issue with an NTPD whereby it's defaulting (or
>> whatever the correct terminology is) to the LOCAL clock, this is
>> occurring when one of our servers loses connectivity. We have 4
>> server's setup and the local clock is also configured:
>>
>> server 127.127.1.0 # local clock
>> fudge 127.127.1.0 stratum 10
>>
>> ntpq -p output:
>>
>> remote refid st t when poll reach delay offset jitter
>> ==============================================================================
>> hostname .INIT. 16 u - 1024 0 0.000 0.000 0.000
>> hostname .INIT. 16 u - 1024 0 0.000 0.000 0.000
>> hostname .INIT. 16 u - 1024 0 0.000 0.000 0.000
>> hostname.INIT. 16 u - 1024 0 0.000 0.000 0.000
>> *LOCAL(0) .LOCL. 10 l 9 64 377 0.000 0.000 0.001
>>
>> The issue with this is that once it defaults to the LOCAL, it doesn't
>> sync with an external source again, until we manually restart
>> ntpd. I'm sure this is something simple, but I'm hoping someone can
>> assist.
>
> Patient: Doctor, it hurts when I do this!
> Doctor: Then don't do that. Next patient!
>
> Why do you have LOCAL in your ntp.conf? It is almost always a REALLY bad
> idea because it leaves the clock free-running.
>
> It is oft discussed on this list why so many software distributions
> include LOCAL in the default ntp.conf. They really, really should stop
> doing it and so should you.
>
> The real question is why you are not getting to any of the named servers
> in ntp.conf.
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