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Date: Tue, 25 Jul 2006 08:50:42 -0700
From: Tim Kientzle <kientzle@freebsd.org>
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Cc: freebsd-hackers@freebsd.org
Subject: Re: FBSD 5.5 and software timers
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M. Warner Losh wrote:
> In message: <B3BCAF4246A8A84983A80DAB50FE72424C6970@secnap2.secnap.com>
>             "Michael Scheidell" <scheidell@secnap.net> writes:
> : > I presume the servers are all stable (ie not stepping) and 
> : > have a reasonably low delay.  If so, I suspect your ntpd PLL 
> : > has locked up. I've seen problems with some versions of ntpd 
> : 
> : 20 different machines?
> 
> That would strongly imply a poor choice of upstream server.

It might also help to set up 1 machine as
your NTP master.  Have it sync to the upstream
servers and have the rest of your machines
sync to it.  This won't solve the problem,
but might make it easier to solve (once your
NTP master is stable, the rest should follow).

You can experiment with different upstream
servers, different network settings, different
NTP settings, etc.

Tim

P.S. ntp docs outline the following as "best practice":
Use 2 local machines as NTP masters, each syncing
to a completely different set of upstream
masters.  The rest of your machines sync to
both of your local masters.  This is supposed
to protect you against a wide variety of
timekeeping failures.