[ntp:questions] Re: ntp sanity limit kills ntp daily

Heiko Gerstung heiko.gerstung_removeme_ at meinberg.de
Wed Jun 15 14:59:55 UTC 2005

My 2c :

Brian T. Brunner schrieb:
> has been suggested.  My opinion (get things done now, figure out who to blame and shoot later)
> is that the backup script should start at beginning, and stop at end, a small script that does 
> while `true`;do hwclock --hctosys;sleep 1;done
> This will keep the system time up-to-the-second, so ntp doesn't go berserk.

I'm not sure if ntpd likes to find out another process is messing around 
with the clock. My workaround would be:

- stop ntpd
- run backup
- get time back with ntpd -q -g or ntpdate
- start ntpd

However, if you need the correct time during your backup sessions (if 
you need logfiles to be correct or whatever), I'd use Brian's small 
script as an additional step. Fire it up after you stopped NTP and stop 
it after the update has been completed.

> Also, the backup itself should be 'nice'd to permit the hwclock script to run, of course.

Maybe this could slow down the whole show. I'd reduce the calls to 
hwclock to once a minute (sleep 60), but all depends on how accurate 
your time needs to be during backup.

If you really depend on this, you should go and try another hardware.

Kind regards,


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Cool, now I know a secret ;-)

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