[ntp:questions] Re: NTP sync on a standalone network (Windows 2k)

Hal Murray hmurray at suespammers.org
Fri Aug 18 08:26:51 UTC 2006


>I feel there is a risk of too much drift is my solution is based on only one 
>server providing the time to all the others... because this network is 
>isolated from the real world (let's say it's a bunker). If the main server 
>drift, all the rest of the system will drift.
>My thought was that by peering the servers, that would minimise the drift. 
>If one drift, the others would tell hom : "hold on mate, you're drifting too 
>far"

Using a single system as the master seems like a reasonable approach
to me.  It's simple so you can understand it.  Just fixup the time
by hand when it drifts too far off.

The main source of error in most systems is the initial accuracy
of the crystal when it comes from the factory.  That's a constant.
You can measure it and correct for it.  After that, your systems
will keep pretty good time.  (That's how we used to do it before
NTP.)

The next source of error is the shift in frequency as the temperature
changes.  Is the temperature in your bunker stable?  If so, that
helps a lot.

Is the load on your system stable or bursty?  Self heating is important.
It might help to allocate a separate box to being your NTP server.

adjtimex is the utility to tweak the clock frequency.

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