[ntp:questions] [SOLVED] Default config on Ubuntu doesn't work as client

David Woolley david at ex.djwhome.demon.co.uk.invalid
Tue Mar 11 07:30:20 UTC 2008


Michael B Allen wrote:
> The following config works:
> 
>   driftfile /var/lib/ntp/ntp.drift
>   server 192.168.2.15 iburst
> 
> The clock was sync'd in a matter of seconds.
> 
> I kinda figured it would work since I have other servers that use it
> and I've asked about this on this list before and was told that the
> above was the minimum client config. I was just intrigued that Ubuntu

It's not minimum; it includes some, but not all, of the optional things 
that are considered best current practice (it doesn't contain 4 servers, 
which is the other common BCP requirement).

Given that your drift rate is 6666 ppm and ntpd needs it to be somewhat 
less than 500ppm, I suspect you are getting a continuous sequence of 
steps and you just happened to look after a step (and iburst is allowing 
  it to actually get a time measurement fast enough that it does exceed 
128ms before the time is measured.

I don't know how VMWare handles the TSC, but unless it handles it in a 
away intended for real time measurement, rather than CPU usage 
measurement the calibration may be run at a time that doesn't match 
average conditions.  If that theory is correct, you need to disable TSC 
as a time source.

> could ship with a default config that didn't actually work and wanted to
> see if someone could pinpoint why. I have a feeling there are a lot of
> Ubuntu users out there who think their clocks are syncing when in fact
> they're not.
> 
> Thanks for the entertainment,
> Mike




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