Preventing ntpd from adjusting time (backwards)

[Chuck Swiger]

On Apr 21, 2009, at 11:57 AM, Mel Flynn wrote:
[ ... -x option... ]
> Hmm, that might work. Thanks!

Sure.

>> It should be surprising that your clock would jump by 6 seconds.  Do
>> you have adequate upstream timesources (ie, at least 4) configured,  
>> is
>> your local HW clock busted somehow, or are you doing something odd
>> with power-savings mode or running in a VM or something...?
>
> One timesource, shared on local network, this machine is a client of  
> the
> gateway, which uses only one source (ntp.alaska.edu, which is  
> geographically
> 10 minutes by car but thanks to Alaska bad peering, we go through  
> Seattle
> anyway). I checked the logs, that machine didn't step at all that  
> day (or any
> other day, as far as my logs go). It always happens after reboot, as  
> Matthew
> indicated. No VM, no power-savings. The only odd things are  
> Hyperthreading and
> the reboot.

OK, a step upon boot is not unusual-- some machines have poor  
timekeeping with the internal BIOS/battery-backed clock used when the  
system is off.

Note that NTP falseticker detection really wants to have at least 4  
timesources available for the algorithm it uses to detect whether an  
NTP source is behaving poorly.  Try contacting your ISP for nearby NTP  
sources, or try adding 0.us.pool.ntp.org, 1.us..., & 2.us... to your  
config; the NTP pool nameservers use a geolocation mechanism to some  
extent to try and return NTP servers which are close.

Regards,
-- 
-Chuck