NTP Configuration on RHEL 5.4

max_min · January 12, 2010, 12:49am

Hi,

I'm trying to configure NTP client, however it failes to sync correctly.
Even after I manually set the time, once it connects with the NTP server, it pushes the time ahead by 4 hours.
We have set an AIX host as NTP server. It works fine for other AIX hosts, however fails on RHEL 5.4


[root@mpr21r08 ~]#
[root@mpr21r08 ~]# date
Tue Jan 12 07:48:55 SAST 2010
[root@mpr21r08 ~]# hwclock
Tue 12 Jan 2010 07:49:13 AM SAST  -0.850446 seconds
[root@mpr21r08 ~]# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*app03r03        LOCAL(0)         4 u 4971  512  377    0.168    0.697   0.598
[root@mpr21r08 ~]# service ntpd restart
Shutting down ntpd:                                        [  OK  ]
ntpd: Synchronizing with time server:                      [  OK  ]
Starting ntpd:                                             [  OK  ]
[root@mpr21r08 ~]# date
Tue Jan 12 11:49:51 SAST 2010
[root@mpr21r08 ~]# hwclock
Tue 12 Jan 2010 07:49:55 AM SAST  -0.711595 seconds
[root@mpr21r08 ~]# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 app03r03        LOCAL(0)         4 u   18   64    1    0.213    0.043   0.001
[root@mpr21r08 ~]#

Meert · January 13, 2010, 3:43am

Maybe this helps:

Every clock has a value that differs from 'real time'. A quartz based eletronic clock keeps imperfect time, but maintains a very consistent inaccuracy. This base 'inaccuracy' is known as 'time skew' or 'time drift'. Each time the clock is set with hwclock (e.g. during shutdown), hwclock calculates the difference between the new value and previous values and calculates a mean difference. This difference is recorded in the file /var/lib/hwclock/adjtime and in an hourly cron job. Arch Linux adjusts the hardware clock according to the recorded drift. If you are seeing large changes to your hardware clock, it is likely because a large drift is recorded in /var/lib/hwclock/adjtime. This can happen if you have set the hardware clock time incorrectly, or your time standard is not syncronized with a Windows or Mac OS install. To fix this remove /var/lib/hwclock/adjtime, set the correct hardware clock and system clock time, and check if your time standard is correct.

source:Time - ArchWiki

Lazydog · January 19, 2010, 2:38pm

Make sure you have the proper timezone selected as your local time.
It can be set using /usr/sbin/timeconfig

Loic_Domaigne · January 19, 2010, 3:06pm

Correct timezone would be also where I would look at.

Lo�c.

max_min · January 28, 2010, 12:55am

well... I ended up setting a NTP server on another Linux box and it works fine...
So Linux host sync'ing with a Linux NTP server works....
Don't know if Linux host not sync'ing with AIX NTP server is a bug or unsupported configuration... anyways, my needs are fulfilled