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

Robin Laing Robin.Laing at drdc-rddc.gc.ca
Tue Feb 8 18:24:19 UTC 2005


Peter Kiem wrote:
> Hi,
> 
> I've got a FC3 machine where the system clock ADVANCES at a rapid rate 
> which screws up the services I have running.
> 
> I've got a hardware router (Snapgear SME575) which exposes an NTP server 
> to my network and I can successfully use ntpdate to update the clock as 
> long as I do it every 2 minutes.
> 
> In the FC3 machine I have the following ntp.conf
> /etc/ntp.conf:
> restrict default nomodify notrap noquery
> restrict 127.0.0.1
> server 202.173.151.129
> driftfile /var/lib/ntp/drift
> broadcastdelay  0.008
> keys /etc/ntp/keys
> 
> When I look at what NTP is doing I see:
> # ntpq -p
>      remote           refid      st t when poll reach   delay   offset
>  jitter
> ============================================================================== 
> 
>  fizban.zordah.n 0.0.0.0          5 u   31   64  377    1.038  -393692
> 29073.0
> 
> So from what I can NTP is working and can contact the NTP server on my
> router but the time is changing so fast NTP cannot keep up?
> 
> Has anyone experienced/solved this issue?
> 

I looked at mine and I find that the offset and jitter are much 
smaller.  From the following link, the offset should be less.

Now I do remember many years ago reading that if your system time is 
out by to much, it won't be updated.  If your time is out, you may 
have to manually reset it.  Also look at the drift file as if this is 
out, your clock will run at the wrong pace.  You may have to delete 
this file and start again.

http://networking.ringofsaturn.com/Protocols/ntp.php
http://ldp.paradoxical.co.uk/LDP/sag/html/x2883.html

Also, is your BIOS clock set to UTC or local time?  This makes a 
difference from my experience.  One test to make is to check the time 
in bios, shut the computer down and then check the time in bios after 
an hour.  This will give you an indication if the hardware (bios) 
clock is running and how precise it is.  If it is running pretty 
accurate, then I would suspect that the software clock is running 
fast/slow due to the drift setting.

I used to use "hwclock" in the past.

-- 
Robin Laing




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