[lug] Time Warp

David L. Anselmi anselmi at anselmi.us
Tue Feb 21 19:29:32 MST 2006

Paul E Condon wrote:
> On Tue, Feb 21, 2006 at 04:19:58PM -0500, Gordon Golding wrote:
>> I have a server that every once in a while, changes it's time -
>> maybe once a week?  I look at it and it's fine for a few days and
>> then at 13:31 the date says it's 7:31.  (6 hours...?)  I thought
>> there might be some script doing it, but I checked crontab for all
>> the added users and root and there is nothing there.
>>I have a little script running now to grab 'date' regularly, so I can see when it happens.
>>I'm in the correct timezone; Denver, not using NTP.

Are you in the correct time zone?  Your message is stamped EST (-0500). 
  Obviously you're using a different machine to mail from but maybe 
things aren't as they seem.

>>Any thoughts?

What does your BIOS clock say (read with hwclock) vs. date?  Does the 
config file that says you are/aren't using UTC on the hwclock match the 
clock?  I'd bet that's the problem and that the time resets when the 
machine boots (a bad battery could be part of the equation).

> I recommend against just turning on NTP. That would result in unobserved jumps of six 
> hours both formard and backward. At least now half the jumps happen when you are watching.

If the machine is always on you should use NTP.  That won't fix this 
particular problem--ntpd will fail if the clock is off by >1000s so you 
won't see jumps if you get 6 hrs off.


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