[CentOS] hwclock problem

Jobst Schmalenbach jobst at barrett.com.au
Thu Nov 11 19:41:45 EST 2010


I run peridocally (from cron) on all of my machines

  30 * * * * root /sbin/hwclock --systohc

All of those machines in question take their time via NTP
from the same local server, and that server gets its time
from a ntp pool.

Now I had to reboot a couple of them two days ago and to my surprise
all had problems with the time upon booting.

Here are the important files:

[root at XXXXXX ~] #>l /etc/adjtime 
0.001687 1289518202 0.000000

[root at XXXXXXX ~] #>l /etc/sysconfig/clock 

So from my understanding the hwclock should contain the local time.

[root at XXXXXX ~] #>date
Fri Nov 12 11:26:23 EST 2010
[root at XXXXXX ~] #>hwclock
Fri 12 Nov 2010 11:26:42 EST  -0.167976 seconds
[root at XXXXXX ~] #>

However on boot I get the following:

Nov 10 19:08:37 XXXXXX syslogd 1.4.1: restart.
Nov 10 19:08:37 XXXXXX kernel: klogd 1.4.1, log source = /proc/kmsg started.
Nov 10 19:08:37 XXXXXX kernel: Linux version 2.6.18-164.11.1.el5 (mockbuild at builder10.centos.org) (gcc version 4.1.2 20080704 (Red Hat 4.
1.2-46)) #1 SMP Wed Jan 20 07:32:21 EST 2010
Nov 10 19:08:37 XXXXXX kernel: Command line: ro root=/dev/sda2 vga=791
Nov 10 19:08:37 XXXXXX kernel: BIOS-provided physical RAM map:
Nov 10 19:08:51 XXXXXX kernel: IPv6 over IPv4 tunneling driver
Nov 10 08:08:52 XXXXXX ntpdate[2464]: step time server offset -39599.950905 sec
Nov 10 08:08:52 XXXXXX xinetd[2447]: xinetd Version 2.3.14 started with libwrap loadavg labeled-networking options compiled in.

and off course dovecot falls over too "Time just moved backwards by 39599 seconds."

Now, 39600s is 11 hours, which is (inc DST) *MY* offset from Greenwich.

So what am I doing wrong?
The idea of running hwclock is to make sure that exactly the problem with dovecot does NOT occur, and ntp does not have a coughing fit when the hardware clock is not close to the correct time upon booting.
The last time I booted some of those machine was more than 200 days ago, so the hwclock will be skewed if I do not update it.


Keyboard not found - please clean up desktop!

  | |0| |   Jobst Schmalenbach, jobst at barrett.com.au, General Manager
  | | |0|   Barrett Consulting Group P/L & The Meditation Room P/L
  |0|0|0|   +61 3 9532 7677, POBox 277, Caulfield South, 3162, Australia

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