[Dovecot] May 05 07:20:21 imap: Warning: Time jumped forwards 16 seconds

[Jerry]

On Thu, 5 May 2011 23:43:25 +0200
Lorens Kockum <dovecot.fdop at tagged.lorens.org> articulated:

> On Thu, May 05, 2011 at 07:54:50PM +0100, Spyros Tsiolis wrote:
> > 
> > Seriously ?
> 
> Yes, Timo was (of course) both serious and correct.
> 
> ntpdate takes one or more NTP servers as parameters, and sets
> your server's time to match that of the NTP servers. That may
> well cause a jump, even a massive jump.
> 
> ntpd takes a list of NTP servers in its configuration file,
> and uses them to make continual small adjustments. I seem to
> remember that in some cases it is even capable of adjusting the
> speed of your system clock according to its measurements. If the
> difference is too great it will refuse to function and exit with
> an error.
> 
> The usual way is to run ntpdate with -b option once at boot
> (just after the network comes up and long before things like
> dovecot and MTAs get started), and then start up ntpd.
> 
> The other way is to run ntpdate frequently, against an NTP
> server you trust. It's not as good, but sometimes there may be
> objections against running daemons, and if you're aiming at a
> well-behaved NTP server the jumps should be minimal.
> 
> When running ntpd, the essential thing is to check that
> it's actually doing its job. You do that with the command
> "ntpdc". That will drop you to a prompt. The essential commands
> are
> 
> 	sysinfo
> 	peers
> 	server x.x.x.x
> 	sysinfo
> 	quit
> 
> sysinfo should give your stratum as somwhere between 3 and 5 (if
> it's less you're probably doing something wrong, and if it's 16
> you're not synchronized). peers should give one * sign in the
> first column and some number of + signs.
> 
> After that overview, man ntpdate, man ntpd, and google :-)
> 
> HTH.

On a FreeBSD machine, putting the following two lines into the
"/etc/rc.conf" file will cause "ntp" to be started and force it to
synchronize the time regardless of how far out of sync it actually is.

ntpd_enable="YES"                    # Start time server
ntpd_sync_on_start="YES"             # Synchronize on start

Of course, you still need to have a default ntp.conf file.

-- 
Jerry ✌
Dovecot.user at seibercom.net

Disclaimer: off-list followups get on-list replies or get ignored.
Please do not ignore the Reply-To header.
__________________________________________________________________