[ntp:questions] Not-So-Newbie question

Martin Burnicki martin.burnicki at meinberg.de
Mon Feb 25 10:26:55 UTC 2008


Peter Laws wrote:
> Yesterday, I added another Stratum 2 to the group and for some reason, it
> seems to be taking a long time to get stabilized.  Part of the problem, I
> think, is that it's running off a Knoppix CD (it's an NPAD test system). I
> worked around the fact that the drift file, by default, had 0.00 in it,
> but I don't think that's an issue since I've restarted the daemon a number
> of
> times tweaking things.  Other systems of the same HW type didn't take this
> long.

Maybe it's a problem of the Linux kernel version you are using. There have
been quite a few reports where recent kernels were unable to keep good time
on certain hardware. If the system clock timekeeping is bad (with jitter)
then ntpd has not much chance to discipline it.

> My real question is this:  What am I really looking at in the offset and
> jitter columns?  What makes a "good server" in terms of ntpq -p output?
> Low offset?  Low jitter?  Some combination?

Depending on what causes the jitter and offset. If timekeeping by the kernel
is poor the this may also cause high jitter and offsets.

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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