[ntp:questions] Is 24PPM an Excessive Real-Time Clock Correction?
Richard B. Gilbert
rgilbert88 at comcast.net
Thu Jul 5 19:45:52 UTC 2007
David T. Ashley wrote:
> I have ntpd running on a RHEL Linux Dell 1U rack server in another city.
> I have no experience with other servers (to know how accurate the clocks are
> or are not).
> The value of "drift" that gets settled on after a few days is 24 PPM (about
> 14 seconds/week).
> This strikes me as a little high, because even my $20 Timex watch does
> better than this.
> Any insight into whether 24 PPM is excessive for my server?
Consider that a computer manufacturer typically spends something like $2
US on the components for the clock! Consider, also, that they provide
no way to adjust the clock hardware. Computers are designed to compute,
not to keep time. The original IBM PC and PC/XT did not even have a
clock; if you wanted a clock it was an add-on at extra cost from a third
24 PPM is pretty good. Anything up to a hundred or two will usually
work just fine.
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