[ntp:questions] Re: NTP and Cron
Steven.Hajducko at DigitalInsight.com
Tue Nov 30 17:50:54 UTC 2004
>What you are are describing is not supposed to happen! I find it
>difficult to believe that a properly working ntp setup would allow the
>time to get out of synch by 14 seconds. If it did, somehow, get that
>far off it would step but the step you cite is in the positive
>direction; it is setting the clock ahead, not back, and cron should not
>see the same time twice.
Well, good to know that it's a positive step, which means that this probably
wasn't the problem.
> Please provide some more details. "cron jobs" suggests some Unix or
> Linux variant but which one? Which version of the NTP software are you
> running? On the chance that NTP is not properly configured, would you
> consider posting your ntp.conf file? What options are you specifying
> when you start ntpd?
It's AIX 5.2, ML 4. NTP v. = 3.4y ( This is from the logs, not sure if
that's correct, didn't install it ).
The NTP.conf is minimal -
In AIX, we start it as a subservice with no arguments specificed on the
commandline. ie ( startsrc -s xntpd ).
> Finally, assuming that ntp stepping the clock in either direction caused
> the problem, I fail to see how a "monitoring script" could prevent a
> recurrence! You might be able to detect a large clock step but you
> would probably be too late to prevent a second instance of a job from
It wasn't meant to prevent. It was meant to warn when it happened again.
However, I would rather learn how to prevent this problem then trying to
figure out a way to figure out when cron is firing off duplicate jobs in an
inappropriate time span. ( Something that sounds a lot harder than trying
to get NTP configured correctly! :) )
> I believe the most effective prevention would be to locate the error
> that caused the clock step and prevent a recurrence of that!
Totally agreed. I'd just like to figure out if it was possible and if it
was, what we could do to prevent it. :)
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