[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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