Jobst Schmalenbach wrote:
Hi.
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@XXXXXX ~] #>l /etc/adjtime
0.001687 1289518202 0.000000
1289518202
LOCAL
[root@XXXXXXX ~] #>l /etc/sysconfig/clock
ZONE="Australia/Melbourne"
UTC=false
ARC=false
So from my understanding the hwclock should contain the local time.
[root@XXXXXX ~] #>date
Fri Nov 12 11:26:23 EST 2010
[root@XXXXXX ~] #>hwclock
Fri 12 Nov 2010 11:26:42 EST -0.167976 seconds
[root@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@xxxxxxxxxxxxxxxxxxxx) (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 192.168.1.1 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.
Last time I checked the shut down of a machine writes the system time to
the H/W prior to reboot. Thus the problem you describe should not occur
if proper shutdown occurs. HTH
Jobst
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