ntpd struggling to keep up - how to fix?

[Jeremy Chadwick]

On Thu, Feb 11, 2010 at 07:06:52PM +0100, Torfinn Ingolfsen wrote:
> Hi,
> 
> One of my machines, the fileserver-with-zfs-to-be[1] has trouble
> keeping correct time. Or rather, ntpd is struggling.
> In /var/lkog/messages I see this:
> Feb  7 12:05:54 kg-f2 ntpd[909]: ntpd 4.2.4p5-a (1)
> Feb  7 12:11:16 kg-f2 ntpd[910]: time reset +1.020413 s
> Feb  7 12:11:16 kg-f2 ntpd[910]: kernel time sync status change 2001
> Feb  7 12:26:26 kg-f2 ntpd[910]: time reset +2.277793 s
> Feb  7 12:41:29 kg-f2 ntpd[910]: time reset +2.260229 s
> Feb  7 12:57:02 kg-f2 ntpd[910]: time reset +2.332972 s
> Feb  7 13:21:24 kg-f2 ntpd[910]: time reset +3.659869 s
> Feb  7 13:37:01 kg-f2 ntpd[910]: time reset +2.343230 s
> Feb  7 13:52:24 kg-f2 ntpd[910]: time reset +2.310659 s
> Feb  7 14:07:29 kg-f2 ntpd[910]: time reset +2.265705 s
> Feb  7 14:23:03 kg-f2 ntpd[910]: time reset +2.335868 s
> Feb  7 14:39:06 kg-f2 ntpd[910]: time reset +2.411116 s
> Feb  7 14:54:32 kg-f2 ntpd[910]: time reset +2.318222 s
> Feb  7 15:09:55 kg-f2 ntpd[910]: time reset +2.308120 s
> Feb  7 15:25:49 kg-f2 ntpd[910]: time reset +2.388391 s
> Feb  7 15:40:54 kg-f2 ntpd[910]: time reset +2.265464 s
> Feb  7 15:55:57 kg-f2 ntpd[910]: time reset +2.257952 s
> Feb  7 16:11:45 kg-f2 ntpd[910]: time reset +2.373325 s
> 
> and this goes on an on, forever. At any give time, no matter how long the machine has been up, ntpq ca report this:
> root at kg-f2# ntpq -p
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
>  kg-omni1.kg4.no 129.240.64.3     3 u   13   64   37    0.162  703.094 444.681
> 
> Note: all machines on my LAN use my firewall as the ntp server. 
> The ntp server runs FreeBSD, none of the other machines have any trouble keeping time.
> My workstation for example:
> tingo at kg-v2$ ntpq -p
>      remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> *kg-omni1.kg4.no 129.240.64.3     3 u   44   64  377    0.138    4.018   0.338
> (my workstatuion also runs FreeBSD 8.0-stable / amd64)
> 
> The machine runs FreeBSD 8.0-stable / amd64:
> root at kg-f2# uname -a
> FreeBSD kg-f2.kg4.no 8.0-STABLE FreeBSD 8.0-STABLE #2: Sun Jan 31 18:39:17 CET 2010     root at kg-f2.kg4.no:/usr/obj/usr/src/sys/GENERIC  amd64
> 
> So, how can I get the machine to keep time / get ntpd synchronised?
> 
> References:
> 1) hw info: http://sites.google.com/site/tingox/ga-ma74gm-s2h
> 2) FreeBSD info: http://sites.google.com/site/tingox/ga-ma74gm-s2h_freebsd

Your machine has a rapidly drifting clock, usually an indicator of a
hardware problem (crystal gone bad is a common one -- seen this at work
quite a few times), or possibly a bad time counter source chosen by the
kernel.  Can you please provide the output of:

sysctl kern.timecounter

Finally, was this OS installation used on different hardware in the
past?  Meaning: was the hard disk previously installed on another
machine?  Why I'm asking: /var/db/ntpd.drift could be from an old
computer (the previous hardware), and the clock drift rate would be
different than that of your newer[1] hardware.  If that's the case,
please stop ntpd, rm /var/db/ntpd.drift, and restart ntpd.  Be aware it
will take up to 72 hours for the clock drift to be calculated correctly.

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |