dovecot - Nov 2009 - dovecot: Fatal: Time just moved backwards by 3909 seconds.

Hi,

after setting up a KVM based virtual guest on one of our virtualization 
servers, we see dovecot die on that virtual guest regularly because of 
an alleged time shift.

The virtual guest is Centos 5.4 based with dovecot 1.2.8 (at first we 
also tried with the original 1.0.7 (?) dovecot shipped with Centos).

I wrote "alleged time shift" because there is no timeshift whatsoever,
or at least I don't notice it anywhere else.

ntp is - of course ;-) - up and running and no other applications have 
time troubles and I've even disabled the local clock as a time reference.

As a proof that the time did not shift see this log excerpt:

------CUT-------
Nov 29 14:02:22 athesia dovecot: IMAP(atester): Connection closed
Nov 29 14:04:11 athesia dovecot: imap-login: Time just moved backwards 
by 4397 seconds. This might cause a lot of problems, so I'll just kill 
myself now. http://wiki.dovecot.org/TimeMovedBackwards
------CUT-------

So as you see, dovecot successfully logged a message on 14:02 and then 
complained about the time having shifted 4397 seconds on 14:04 ...

Thanks in advance

-- 
Udo Rader, CTO
http://www.bestsolution.at
http://riaschissl.blogspot.com

On 11/30/2009, Udo Rader (listudo at bestsolution.at)
wrote:
> The virtual guest is Centos 5.4 based with dovecot 1.2.8 (at first we
> also tried with the original 1.0.7 (?) dovecot shipped with Centos).
> 
> I wrote "alleged time shift" because there is no timeshift
> whatsoever, or at least I don't notice it anywhere else.
> 
> ntp is - of course ;-) - up and running and no other applications
> have time troubles and I've even disabled the local clock as a time
> reference.
Of course you know not to use ntp on VMs, only on the host, right?

:)

Revent kernels should be able to keep the VM time synced using kvmclock
clocksource...