Preventing ntpd from adjusting time (backwards)
Mel Flynn
mel.flynn+fbsd.questions at mailing.thruhere.net
Tue Apr 21 14:48:56 UTC 2009
On Tuesday 21 April 2009 16:11:52 Tim Judd wrote:
> On Tue, Apr 21, 2009 at 3:39 AM, Matthew Seaman <
>
> m.seaman at infracaninophile.co.uk> wrote:
> > Mel Flynn wrote:
> > > Hi,
> > >
> > > Some coarse reading of ntpd(8) and ntp.conf(5) doesn't lead me to
> > > believe
> >
> > it's
> >
> > > possible to make ntpd *not* adjust the time. With adjust I don't mean
> > > the
> >
> > skew
> >
> > > operation, but really change the time. Backwards is my primary concern
> >
> > but if
> >
> > > it can be turned off completely it's fine with me.
> > >
> > > Reason being dovecot bailing out when this happens:
> > > Apr 1 16:18:26 squish ntpd[1353]: time reset -6.711955 s
> > >
> > > Apr 1 16:18:26 mx1 dovecot: Fatal: Time just moved backwards by 6
> >
> > seconds.
> >
> > > This might cause a lot of problems, so I'll just kill myself now.
> > > http://wiki.dovecot.org/TimeMovedBackwards
> >
> > This seems to be a bete-noir for the dovecot developer. Whatever, it is
> > a royal pain in the arse, as my mailserver always steps the time
> > backwards on each reboot, and then dovecot does it's dying swan thing.
> >
> > Three choices:
> >
> > * Don't run 'ntpd -g' as the documentation tells you is the modern and
> > accepted method. Instead, run 'ntpdate' as a separate process and
> > run 'ntpd' without the '-g' flag.
> >
> > * Don't run dovecot. Other IMAP servers do not suffer in the same
> > way.
> >
> > * Put up with it. Avoid reboots, and swear at all concerned any time
> > you really do have to reboot.
> >
> > Cheers,
> >
> > Matthew
>
> How about adding ntpdate's provided string to dovecot's required string in
> their respective startup rc.d scripts? This forces dovecot to wait until
> ntpdate has been called, assuming time has actually been set/changed, then
> dovecot may start?
That could work, if ntpd_sync_on_start would actually sync on start. Trying
not to enable ntpdate unless I really have to, since I expect it to be gone in
8.0.
Still, there's a chance ntp steps backwards during the runtime, but then my
CMOS battery probably needs replacing anyway.
--
Mel
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