[ntp:questions] Re: ntpd Not Converging
David T. Ashley
dta at e3ft.com
Fri Nov 4 14:31:53 UTC 2005
Thanks to everyone who responded. I do appreciate all of the good advice
about not using Stratum 1 servers during development, etc.
But the replies did not zero in on the key question. It is a control law
question. When ntpd starts and the server time is off of the true time by
an offset (say, 2 seconds), what "control law" does it apply to reconverge
the server's time and the true time?
Again, when I start ntpd with /var/lib/ntp/drift not present, it always
works. I've noticed that ntpd waits about an hour and 15 minutes to use the
time difference to adjust the "frequency" of the kernel timing parameters to
go towards convergence. It is only when the drift file exists that it
doesn't seem to try to converge the server's time and the true time.
I've adjusted my startup to always delete /var/lib/ntp/drift, and this works
fine. But I'd like to understand the control law involved.
By "control law" I mean the discrete time transfer function that influences
the stability and long-term convergence characteristics of the system.
I appreciate all of the replies. But none of them seem centered on the core
issue, which is the control law.
More information about the questions