NTP problem - Clock too fast for NTP to keep up?

[Gene Heskett]

On Wednesday 09 February 2005 23:25, Peter Kiem wrote:
>> I too had the fast clock problem, and by tickling the tick counter
>> with the 'tickadj' command, was able to stay well within 1 second
>> per hour.  The bare command will return the current tick value,
>> default is 10000, but I'm curently setting it at 9926 for accurate
>> time keeping.  This seems to be 2.6 problem as the default is
>> pretty close on a 2.4.29 system running on an elderly TYAN mobo at
>> 500mhz.
>
>Where and how would you set the tickadj parameter?
>Would you set it higher or lower for a system running too fast?

Lower.  Default is 10000.

Setup an ntpdate to hit the net for the time, say hourly.  Put
a tail on the log so you can see how far off it is.

Set tickadj to 9950 and see if it still gains time, if it does,
try 9925.  Here, that was enough to make it start running slow,
and I wound up in the 9926 to 9927 area for get the thing running
within range of the soft only, no step adjustment in ntpdate.

Once fine tuned, stick that tickadj in your /etc/rc.d/rc.local file.

My logs now look like this:
Feb  9 07:37:01 coyote ntpdate[10716]: adjust time server 18.145.0.30 offset 0.244594 sec
Feb  9 08:37:02 coyote ntpdate[11552]: adjust time server 137.146.210.250 offset 0.127282 sec
Feb  9 09:37:03 coyote ntpdate[12388]: adjust time server 130.207.244.240 offset 0.296662 sec
Feb  9 10:37:02 coyote ntpdate[13242]: adjust time server 198.30.92.2 offset 0.241722 sec
Feb  9 11:37:03 coyote ntpdate[30026]: adjust time server 64.5.0.129 offset 0.296659 sec
Feb  9 12:37:02 coyote ntpdate[3448]: adjust time server 137.146.210.250 offset -0.009782 sec
Feb  9 13:37:01 coyote ntpdate[4632]: adjust time server 198.30.92.2 offset 0.668905 sec
Feb  9 14:37:03 coyote ntpdate[5784]: adjust time server 137.146.210.250 offset 0.169233 sec
Feb  9 15:37:01 coyote ntpdate[6964]: adjust time server 130.207.244.240 offset 0.145988 sec
Feb  9 16:37:00 coyote ntpdate[7951]: adjust time server 198.30.92.2 offset 0.315650 sec
Feb  9 17:37:03 coyote ntpdate[8871]: adjust time server 18.145.0.30 offset 0.159681 sec
Feb  9 18:37:00 coyote ntpdate[9720]: adjust time server 18.145.0.30 offset 0.404644 sec
Feb  9 19:37:02 coyote ntpdate[10760]: adjust time server 18.145.0.30 offset 0.172819 sec
Feb  9 20:37:03 coyote ntpdate[12025]: adjust time server 18.145.0.30 offset 0.333407 sec
Feb  9 21:37:02 coyote ntpdate[13107]: adjust time server 198.30.92.2 offset 0.189226 sec
Feb  9 22:37:01 coyote ntpdate[14168]: adjust time server 18.145.0.30 offset 0.412748 sec
Feb  9 23:37:01 coyote ntpdate[15813]: adjust time server 18.145.0.30 offset 0.151833 sec

These logs as you can see are from a near random choice of servers,
the only constant choice offered to ntpdate by the script I use is
pool.ntp.org.  As thats at 61.9.198.77 according to a ping, you can see
that it never responded within the time frame ntpdate expects.  That
does seem a little odd...  Or possibly a bug in how ntpdate selects
the servers when given multiple servers to query.

I have a couple of scripts I use, google for 'linux updateclock'
should find the one I'm using, along with a file listing timeservers,
obviously called timeservers.  My copy is a bit dated, so I've had to
remove a couple of the navy's servers that are no longer responding.

Have fun, with an accurate clock on your x screen. :)

>--
>Regards,
>Peter Kiem
>
>Zordah IT - IT Consultancy and Internet Services
>Ph: (0414) 724-766   Fax: (07) 3344-5827
>Web: www.zordah.net  Email: zordah at zordah.net

-- 
Cheers, Gene
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Copyright 2005 by Maurice Eugene Heskett, all rights reserved.