[ntp:questions] drift value very large and very unstable

Rob Neal hundoj at comcast.net
Tue Mar 4 21:55:50 UTC 2008

On Mon, 3 Mar 2008, Andy Helten wrote:
> I am having a problem with drift values approaching and, on occasion,
> reaching +/-500ppm.
> NTP conf file for BC635 IRIG-B PMC
> /*******************************************************/
> tinker panic 0   # don't let daemon exit for any time difference
> # Base conf file for normal operation for both server and client
> tinker step 0    # disable stepping, so that we only slew time
> # Conf file for normal operation of a server
> server prefer mode 2 minpoll 4 iburst burst # Symmetricom
> BC635
> tos orphan 6
 	-- snippage --

Lose the 'iburst burst' on 16.

With the two tinker commands above you give ntpd the requirement
to amortize the offset entirely with frequency control.

Are you giving it long enough to do so?

If possible, toss those tinker options and try again.

ntpq -p, ntpq -c as -c "rv &x" (where x is the association index
for the refclock 16) and ntpq -crv would be useful.


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