[ntp:questions] Re: SUSE OSS 10 NTPD Clock Drift

Richard B. Gilbert rgilbert88 at comcast.net
Thu Jan 19 19:10:20 UTC 2006

garskof at gmail.com wrote:

>I have 'ntpd' running on a SUSE OSS 10 server that has very bad clock
>drift. This box drifts about 60 to 90 min per day. The 'ntpd' service
>is up and running, and it correctly resets the clock on boot (on
>startup of ntpd), but never resets the clock again.
>How do I tell ntpd to check the time with a time service a few times a
>day to help keep this machine on track? I can not find any
>documentation that tells me how to set how often ntpd checks its
>sources for updates.
>Thanks for any and all info.
You are asking for more than ntpd can do.   The limit on clock frequency 
correction is 500 parts per million (PPM) which works out to about 42 
minutes per day.   Either fix the hardware, replace the hardware, or 
forget about having the correct time.  (Actually, you could run ntpdate 
as a cron job every 30 minutes if you don't mind the clock "jumping" 
when it's reset.)

Actually, it may not be the hardware.  Some flavors of Linux have a 
problem with losing clock interrupts when they get busy.  If you have a 
kernel parameter called "HZ" and if it's set to 1000, setting it to 100 
might help.

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