[ntp:questions] Increase maximum frequency offset to deal with really bad clock
unruh-spam at physics.ubc.ca
Mon Mar 9 23:09:16 UTC 2009
fwayne at frankwayne.com (Frank Wayne) writes:
>While several people suggested that Jeff use guest/host synchronization, no one ever answered the first question, "is it possible to override the maximum offset PPM?"
>From: questions-bounces+fwayne=frankwayne.com at lists.ntp.org [mailto:questions-bounces+fwayne=frankwayne.com at lists.ntp.org] On Behalf Of jeff at sailorfej.net
>Sent: Wednesday, 28 January 2009 14:46
>To: questions at lists.ntp.org
>Subject: Increase maximum frequency offset to deal with really bad clock
>I have a some FreeBSD systems running as guests in Microsoft Virtual
>Server. There is a known problem with these were the clocks run very
>fast. I am trying to use ntpd to keep their clocks in sync, but the
>frequency error offset is exceeding (I think) ntpd's maximum of 500,
>my driftfile always contains a value of "-500.000". If understand the
>way this works correctly, if I could get the frequency error offset to
>represent the real error rate which I believe to be much higher that
>500 PPM, then ntpd would be able to keep the clocks in sync, as it is
>now, it slowly falls behind until it fails to correct altogether.
>So is it possible to override the maximum offset PPM in the driftfile,
>or is there a better way to fix this?
Recompile. ( Change include/ntp_proto.h
#define SLEW 500e-6
#define SLEW 500e-5
for example to make it 10 times larger. Not sure if this will work or not.
However, you should NOT be running ntp on a virtual system anyway. It makes
little sense since hardware cannot be vitualized.
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