[Dirvish] DST and backups skipping a day

Paul Slootman paul at debian.org
Tue Nov 1 02:13:03 PST 2005


On Mon 31 Oct 2005, Warren Sanders wrote:

> My guess was that it tried running twice... once for 2am and again
> when the clocks turned back at 2am.  Maybe 2:01 would fix this in the
> future?

With a sensible cron daemon that shouldn't be necessary.
>From the manpage of cron(8) on Debian (Vixie Cron):

       Special  considerations  exist when the clock is changed by less than 3
       hours, for example at the beginning and end of daylight  savings  time.
       If  the time has moved forwards, those jobs which would have run in the
       time that was skipped will be run soon after the  change.   Conversely,
       if  the  time has moved backwards by less than 3 hours, those jobs that
       fall into the repeated time will not be re-run.

That said, I almost never schedule tasks for exactly on the hour, to
prevent everything waking up at the same time and causing a heavy load
:)
At work we have a room with about 80 systems running Debian. The power
comsumption is monitored, and you can see an increase at 06:25 when the
cron.daily tasks are run :)


Paul Slootman


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