Time Randomly changes on my server!

[Committed2IT]

Hmmm.
I have Dovecot installed that constantly "commits suicide" due to the constant time changes on my server.

But I don't have any NTPD or anything running..

If I do a

watch date

it updates the screen every 2 seconds, and you can clearly see the time flip back a few seconds, and then go back to the correct time.. Sometimes it goes back a few minutes, and back to normal..

I literally did this 10 seconds ago..

[root ~]# date
Tue Feb 15 17:15:11 GMT 2011
[root ~]# date
Tue Feb 15 17:15:40 GMT 2011
[root ~]# date
Tue Feb 15 17:15:40 GMT 2011
[root ~]# date
Tue Feb 15 17:15:13 GMT 2011
[root ~]# date
Tue Feb 15 17:15:13 GMT 2011
[root ~]# date
Tue Feb 15 17:15:41 GMT 2011
[root ~]# date
Tue Feb 15 17:15:14 GMT 2011
[root ~]# date
Tue Feb 15 17:15:14 GMT 2011
[root ~]# date
Tue Feb 15 17:15:15 GMT 2011
[root ~]# date
Tue Feb 15 17:15:15 GMT 2011
[root ~]# date
Tue Feb 15 17:15:16 GMT 2011
[root ~]# date
Tue Feb 15 17:15:16 GMT 2011
[root ~]# date
Tue Feb 15 17:15:16 GMT 2011
[root ~]# date
Tue Feb 15 17:15:44 GMT 2011
[root ~]# date
Tue Feb 15 17:15:17 GMT 2011
[root ~]# date
Tue Feb 15 17:15:17 GMT 2011
[root ~]# date
Tue Feb 15 17:15:45 GMT 2011
[root ~]# date
Tue Feb 15 17:15:18 GMT 2011
[root ~]# date
Tue Feb 15 17:15:46 GMT 2011
[root ~]# date
Tue Feb 15 17:15:46 GMT 2011
[root ~]# date
Tue Feb 15 17:15:19 GMT 2011
[root ~]# date
Tue Feb 15 17:15:19 GMT 2011
[root ~]# date
Tue Feb 15 17:15:20 GMT 2011
[root ~]# date
Tue Feb 15 17:15:47 GMT 2011
[root ~]# date
Tue Feb 15 17:15:20 GMT 2011
[root ~]# date
Tue Feb 15 17:15:21 GMT 2011
[root ~]# date
Tue Feb 15 17:15:48 GMT 2011
[root ~]# date
Tue Feb 15 17:15:21 GMT 2011

Can anyone suggest anything as this kills my Dovecot quite often!

Feb 15 17:35:02 dovecot: pop3: Fatal: Time just moved backwards by 28 seconds. This might cause a lot of problems, so I'll just kill myself now.

The Dovecot Wiki says

1) You're running ntpdate periodically. This isn't a good idea.
2) You're using some kind of a virtual server and you haven't configured it right (or it's buggy).

...and neither apply to me.

Thanks


CentOS Linux 5.5
Dovecot 2.0.9-1_125.el5

[Rubberman]

Some system configurations and applications can cause the system clock to run slow. It is generally only set once on boot from the hardware real time clock (RTC), but if something is making the system lose time, and something else, such as cron, is periodically running the hwclock system command (which resync's system time with the RTC), then you can experience what you seem to be seeing. At this point, that is just a SWAG, but it is in the realm of possibility.

Myself, I always run ntpd to keep my system time synchronized with the established time base. You really only need one system on a LAN to be synced to an external source (NIST, et al), and the rest of the systems on the LAN can sync to that local server, reducing external network traffic. This can be important on large LAN sites. In fact, on really big LANS, it's not uncommon for there to be one system externally synced, and a server on each subnet that syncs with that one. Then all the other systems, workstations, embedded devices, etc. all sync to their local subnet ntp server. In any case, today there's no excuse for any system to be more than a couple of milliseconds off in time.

One last reason to keep synced with network time (ntp) is that when you reboot or shut down your system, it will sync the RTC with system time (at least on Unix/Linux systems), so if the system time is skewed the RTC will be also. When set via ntp, then you know that the RTC (which is battery backed up) will set the system time correctly on the next boot cycle until it is corrected by ntp.

[Committed2IT]

Some system configurations and applications can cause the system clock to run slow. It is generally only set once on boot from the hardware real time clock (RTC), but if something is making .....................

Hey! Thanks for your reply..
I dont have NTP running on CRON anymore.. I disabled it for this..

Time doesnt change, it "flits" back or forth, and then comes back to normal.. It does this every few seconds of so.

This is a script displaying the results from "DATE" repeatedly.

Mon Feb 21 10:31:04 GMT 2011
Mon Feb 21 10:31:00 GMT 2011
Mon Feb 21 10:31:05 GMT 2011
Mon Feb 21 10:31:01 GMT 2011
Mon Feb 21 10:31:06 GMT 2011
Mon Feb 21 10:31:02 GMT 2011
Mon Feb 21 10:31:07 GMT 2011
Mon Feb 21 10:31:02 GMT 2011
Mon Feb 21 10:31:07 GMT 2011
Mon Feb 21 10:31:03 GMT 2011
Mon Feb 21 10:31:08 GMT 2011
Mon Feb 21 10:31:04 GMT 2011
Mon Feb 21 10:31:09 GMT 2011
Mon Feb 21 10:31:04 GMT 2011
Mon Feb 21 10:31:09 GMT 2011
Mon Feb 21 10:31:05 GMT 2011
Mon Feb 21 10:31:10 GMT 2011
Mon Feb 21 10:31:06 GMT 2011
Mon Feb 21 10:31:11 GMT 2011
Mon Feb 21 10:31:11 GMT 2011
Mon Feb 21 10:31:06 GMT 2011
Mon Feb 21 10:31:12 GMT 2011
Mon Feb 21 10:31:07 GMT 2011
Mon Feb 21 10:31:12 GMT 2011
Mon Feb 21 10:31:08 GMT 2011
Mon Feb 21 10:31:13 GMT 2011

[Rubberman]

Don't run ntp with cron. Start it as a service instead. It will do its own timing to refresh the timebase. As root, run the command: service ntpd start
You can also go to the administration/services UI and enable/start ntpd there. That way, the system can remember to start ntpd on boot without you needing to manually update the configuration file.

[Committed2IT]

Don't run ntp with cron. Start it as a service instead. It will do its own timing to refresh the timebase. As root, run the command: service ntpd start
You can also go to the administration/services UI and enable/start ntpd there. That way, the system can remember to start ntpd on boot without you needing to manually update the configuration file.

I have absolutly no idea why I said I was running it under CRON! Derrr. Sorry.
the service is currently disabled whilst I'm testing these errors..