A ntp client is running ahead of time of our netowork ntp server.

A ntp client is running ahead of time of our netowork ntp server.

Post by chuck.amad » Tue, 30 Jan 2007 20:20:06


Hi List

I have an issue with a ntp client running Linux SuSE 9.3

Our Network ntp server is a Red Hat Linux Advanced Server release 2.1A.

*I initialy had an* error regarding seeing* *"Bad file descriptor"
errors in /var/log/ntp* *then made sure that only one instance of ntpd*
*is running socklist command and ps -auxxx|egrep ntpd thus run * *kill
-9 PID's and restart ntpd /etc/init.d/ntpd restart. This seemed to fix
things and when I run date command volia I thought I fixed it So thus to
test after weekend.
*
*Thus I have checked this morning using date command and I the ntp
client is 20 minutes ahead of our network ntp server.

Thus I have checked the /var/log/ntp lof file::

15 Dec 10:39:14 ntpd[11875]: synchronized to LOCAL(0), stratum 10
15 Dec 10:40:22 ntpd[11875]: synchronized to 10.0.2.3, stratum 3
15 Dec 10:59:44 ntpd[11875]: kernel time sync disabled 0041
15 Dec 11:01:52 ntpd[11875]: kernel time sync enabled 0001

Thus doesn't look that I have an issue.

Please advice and any suggestions welcomed.

Cheers

Chuck


*
*

--
Chuck Amadi
ROK Corporation Limited
Ty ROK,
Dyffryn Business Park,
Llantwit Major Road,
Llandow,
Vale Of Glamorgan.
CF71 7PY

Tel: 01446 795 839
Fax: 01446 794 994
International Tel: +44 1446 795 839

email: XXXX@XXXXX.COM

This email is confidential to the addressee only. If you do not believe
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A ntp client is running ahead of time of our netowork ntp server.

Post by Harlan Ste » Fri, 02 Feb 2007 05:36:40

Please post the output of 'ntpq -p' on this machine.

H

 
 
 

A ntp client is running ahead of time of our netowork ntp server.

Post by chuck.amad » Fri, 02 Feb 2007 23:06:45

Hi Harlan/List

This is my ntp client that is running ahead with time there are getting
the time from a internal stratum server.

client.ntp:~ # ntpq -p
remote refid st t when poll reach delay offset
jitter
==============================================================================
*LOCAL(0) LOCAL(0) 10 l 52 64 377 0.000 0.000
0.001
client.ntp.rok xxx.43.128.xx 3 u 381 1024 377 8.937 -64924.
1018660
server.rokcorp xxx.43.128.xx 3 u 460 1024 377 979.258 -60744.
1020191

I have for tmp measures created a cron job as below::

# Simple but effect email reminder that will prompt Chuck to check
websites and change monthly WWW Guest pwd's.
# Website http://www.yqcomputer.com/ the first day of every month.

#minute (0-59)
#| hour (0-23)
#| | day of the month (1-31)
#| | | month of the year (1-12)
#| | | | day of the week (0-6 with 0=Sunday)
#| | | | | commands


# Crontab entry to update the system clock once a day
# Created by Chuck on Tue Jan 30 10:38:23 GMT 2007
# Trying The NTP client program ntpdate sets the system clock once.
# As real clocks drift, need periodic corrections
0 2 * * * /usr/sbin/ntpdate -s -b -p 8 -u xx.0.2.x
0 6 * * * /usr/sbin/ntpdate -s -b -p 8 -u xx.0.2.x
0 10 * * * /usr/sbin/ntpdate -s -b -p 8 -u xx.0.2.x
0 14 * * * /usr/sbin/ntpdate -s -b -p 8 -u xx.0.2.x
0 18 * * * /usr/sbin/ntpdate -s -b -p 8 -u xx.0.2.x
0 20 * * * /usr/sbin/ntpdate -s -b -p 8 -u xx.0.2.x
0 22 * * * /usr/sbin/ntpdate -s -b -p 8 -u xx.0.2.x

This is working fine on all 3 ntp clients

Thanks in advance

Chuck





--
Chuck Amadi
ROK Corporation Limited
Ty ROK,
Dyffryn Business Park,
Llantwit Major Road,
Llandow,
Vale Of Glamorgan.
CF71 7PY

Tel: 01446 795 839
Fax: 01446 794 994
International Tel: +44 1446 795 839

email: XXXX@XXXXX.COM

This email is confidential to the addressee only. If you do not believe
that you are the intended recipient, do not pass it on or copy it in any
way. Please delete it immediately.


_______________________________________________
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A ntp client is running ahead of time of our netowork ntp server.

Post by Harlan Ste » Sat, 03 Feb 2007 03:52:00

You only have 2 servers and they do not agree on the time so ntpd will
choose neither.

The jitter to these two servers is very high so ntpd will probably never
select either even if they were to agree on the time.

I recommend you look at:

http://www.yqcomputer.com/

http://www.yqcomputer.com/

H
 
 
 

A ntp client is running ahead of time of our netowork ntp server.

Post by davi » Sat, 03 Feb 2007 06:55:46

In article < XXXX@XXXXX.COM >,



Firstly get rid of this. It might just be sufficient to break it on its
own, although I tend to think that your jitter figures are too large to
be explained just by a local clock that is off by 500ppm (assuming that
you are using real references clocks on the servers). However, it is
always going to confuse issues.

Only add it back when all the following are true:

- the system is working well as a pure client;
- you are using it as a server for other machines;
- you expect outages of several hours and you want the sub-clients to
track you very closely during the outage, even though, on average, they
may have worse absolute times.


This jitter is huge. Your clock frequency error is probably very high and
either the correction has hit the end stop, or the local clock has confused
ntpd into thinking it is better even without a correction. It might just
be worthwhile doing rv 0 to find the frequency correction being applied.
(Alternatively, you are using W32Time upstream without a proper reference
and the root dispersion is very high.)


The delay is unusably high. I don't think this can just be from an extreme
frequency error.


0 2,6,10,14,18,20,22 * * * /usr/sbin/ntpdate -s -b -p 8 -u xx.0.2.x

would have been simpler. I hope you have disabled ntpd, as ntpdate
and ntp don't coexist well.

How much does the time step every time this job runs? From that work
out the frequency error in parts per million. Is it more than about
450? If so, you need to get the OS to keep better time uncorrected, before
you start trying to synchronise it. Modern machines should be within
about 20 ppm.

You are running 70 seconds fast, so lost interrupts aren't a prime
cause in this case. Other options are:

- conflicting time synchronisation software;
- motherboard crystal broken;
- power management is making the TSC calibration unreliable;
- your root server is running W32Time with only its own clock as
reference (use assoc and rv to find out the root dispersion).


The clock that is used by ntpd is not the RTC, it's the clock that decrements
a CTC used for software timing.

Note that you are in FAQ territory, so reading the archives would be a good
idea.


Strange concept of confidential. Do you always mean every sentient
being within the light cone of the posting is allowed to read your
confidential documents?
 
 
 

A ntp client is running ahead of time of our netowork ntp server.

Post by Uwe Klei » Sat, 03 Feb 2007 07:51:09

Hi,
if your clock is gaining fast and has high jitter:

There is an issue with at least some nForce2 nVidia MoBos gaining on the
clock because of apic routed timer interrupts being counted twice on
occasion this is agravated by enabling spread spectrum for the clocks.

You may try to boot your SuSE system with "noapic" as boot option
or boot the "Savesettings" entry.
 
 
 

A ntp client is running ahead of time of our netowork ntp server.

Post by chuck.amad » Sat, 03 Feb 2007 18:57:39

Hi Uwe

Thanks for the pointer.

Unfortunatley I am still learning the network topology as I have just
moved on from a previous Sysadmin job.
So I have saved the tp in my mail NTP folder and when I get the
opportunity to reboot the boxes will try the "noapic"
as the boot option.

Cheers

Chuck


--
Chuck Amadi
ROK Corporation Limited
Ty ROK,
Dyffryn Business Park,
Llantwit Major Road,
Llandow,
Vale Of Glamorgan.
CF71 7PY

Tel: 01446 795 839
Fax: 01446 794 994
International Tel: +44 1446 795 839

email: XXXX@XXXXX.COM

This email is confidential to the addressee only. If you do not believe
that you are the intended recipient, do not pass it on or copy it in any
way. Please delete it immediately.


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