[ntp:questions] Re: High NTP drift values, time resets and hwclock command

Richard B. Gilbert rgilbert88 at comcast.net
Thu Jul 27 03:03:49 UTC 2006

Danny Mayer wrote:
> Sergio Ferruchi wrote:
>>My ntp.conf file of the front server looks as follows:
>>restrict default ignore
>>Additionally I use a hwclock -systohc command every 10 minutes by a
>>cron job to update the hwclock periodically to be able to have a valid
>>hardware clock in case of the blade is not shutdown properly and
>>shutdown script is not executed at all. Could it be that hwclock call
>>can confuse the NTP protocol?
> Never do this. You need to leave it to NTP to control the clock. It
> knows better what it's doing. It may very well be the main cause of your
> problems. Who advised you to do this?

He's talking about the hardware clock, the one that runs on a battery 
when the power is off and is used, or can be used, for an initial 
approximation of the correct time.  AFAIK ntpd does not control that and 
setting it should not affect ntpd.

OTOH setting it every ten minutes seems like overkill; if it gains or 
loses a significant amount of time in ten minutes, it's going to be 
REALLY wrong after the power has been off for an hour or two.

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