[ntp:questions] ntpd -q and driftfile

David J Taylor david-taylor at blueyonder.co.uk.invalid
Tue Mar 22 17:44:51 UTC 2011


"unruh" <unruh at wormhole.physics.ubc.ca> wrote in message 
news:slrniohmmc.6v5.unruh at wormhole.physics.ubc.ca...
[]
> ntpd -q is a replacemtn for ntpdate, which was typically run from cron,
> and he is doing, and it is an "acceptable" procedure if for example you
> do not want a daemon running which could have (unknown to you) security
> issues. It is also a bit unclear how to switch off the server role of
> ntpd and he may not want others querying his machine. On the other had
> it comes at a cost of far worse clock discipline and the probability of
> the computer jumping backwards in time.

For a one-off invocation, "acceptable", but to use it for repeated 
periodic invocations would require further justification, in my view.

> One hour? More like 10 hr. ntpd is really bad at recovering from
> changes, and switchon is a big change.
> After 1 hr the drift is liable to be way off, as ntpd alters the drift
> to bring the clock back into line.

In my experience, NTP writes the drift file every hour, not every ten 
hours.  Even after one hour, the drift value is likely to be of more use 
than no drift value at all.

Cheers,
David 




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