Hermann Hastig wrote:
Hi,
Johan Swenker wrote:
Last summer something similar happened to me. but it strongly depended on
my configuration. So please tell us about your configuration (like
operating system etc.)
It's a plain Linux 2.4 kernel on a Linux from scratch system, nothing
extra that plays with the system's clock. The machine is located in a
fairly large datacenter and does not have any other clock source than
the three upstream servers from de.pool.ntp.org.
So, I think I can say that the datacenter's network connection has
definitly been stable as is the case with the temperature (as Richard
guessed), and there's also no external clock that could mess things up
somehow.
I've watched the clock the last days. The drift file stays at 9.642
while the offsets to the (new) servers move between 1 and 20 ms (except
one that keeps shifting stratum between 3 and 5 and shows offsets up to
83 ms).
I'd consign the server "shifting stratum between 3 and 5" to the garbage
can if I were you!
Seems pretty fine to me (I don't care if the clock's a second wrong or
not). Or am I wrong here?
If your clock is off by as much as one second, something is wrong
somewhere. I expect, and usually get, offsets less than twenty
milliseconds using only internet servers. I do much better than that
with a GPS reference clock. Some servers are not very reliable,
especially those synchronized by an HF radio signal but if you configure
four or five it's easy to see which servers are not delivering good time.
About that maxpoll setting: Of course the offset may grow larger the
longer the poll interval which in turn makes it more difficult to keep
the local time right. But doesn't ntpd automatically keep the poll
interval within limits that still allow to slew the clock, or does it
simply go up until maxpoll, whatever may happen?
The MAXPOLL setting does not mean that ntpd will ever increase the
polling interval to that value. I do believe, however, that capping the
poll interval at 2^10 seconds has some value in preventing a situation
where it might take hours or days to correct an error.
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