[ntp:questions] Stability problem on PowerEdge (SuSE 9.3)

Steve Kostecke kostecke at ntp.isc.org
Tue Feb 27 00:26:55 UTC 2007

On 2007-02-24, Till Wimmer <news-dfn at substring.ch> wrote:

> Our main server is running SuSE 9.3 on AMD64. I installed the xntp
> package from SuSE (Vers. 4.2.0a-35). Hardware: DELL Power Edge 2850
> uanme -a:
>   Linux office #1 SMP Tue Nov 28 13:39:58 UTC 2006 x86_64 x86_64 x86_64 GNU/Linux

> /etc/ntp.conf:

>   server
>   fudge stratum 13

You should comment out the LocalCLK until you fix your stability
problem. And then, you should only re-enable the LocalCLK if you
understand why you need it.

>   server 0.debian.pool.ntp.org iburst
>   server 1.debian.pool.ntp.org iburst
>   server 2.debian.pool.ntp.org iburst
>   server 3.debian.pool.ntp.org iburst

Some people will tell you that this is a poor choice of servers (e.g.
due to excessive delay). That may be true but it's not germane to your

>   disable auth

Disabling auth is not usually a good idea because it can allow someone
with ntpdc to tinker with your ntpd settings remotely. BUT ... this has
nothing to do with your problem.

> Short after starting, everythings looks ok:


> But after 3..5 hours all peers are rejected (ntpq> as) and LOCAL(0) is
> the sync source.

We need to see 'ntpq -p' after your ntpd has been running for those 3-5
hours. We also need to see any ntpd messages in your syslog for that
same period.

> Now i found that pps stability is always 512ppm and pll has a huge offset.

You're not using PPS. Look at the PLL frequency, not the PPS stability.

> ntpdc> kern:
>   pll offset:           4294.95 s
>   pll frequency:        22.694 ppm

The offset is large because your system has been coasting on the
Undisciplined Local Clock and ntpd has not had been able to determine
the right PLL frequency.

> I can't believe that the clock of this server is this terribly
> inaccurate... IMHO it's "professional" hardware. At least it was
> expensive ;)

Price and quality are not always synonymous.

Steve Kostecke <kostecke at ntp.isc.org>
NTP Public Services Project - http://ntp.isc.org/

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