Date: Sat, 13 Mar 2010 19:08:38 +0000 From: RW <rwmaillists@googlemail.com> To: freebsd-questions@freebsd.org Subject: Re: ntpdate problem Message-ID: <20100313190838.2197cdc8@gumby.homeunix.com> In-Reply-To: <4B9BD37E.1060801@infracaninophile.co.uk> References: <3f1c29e71003120257h23ecc310w730bbc6396b27a37@mail.gmail.com> <795fc2b81003120622o2162463dv6697e26a86188cbe@mail.gmail.com> <20100312145405.742da070@gumby.homeunix.com> <3f1c29e71003120706q692fbc1cgebd2463dcf95b35d@mail.gmail.com> <20100312152732.377a92a2@gumby.homeunix.com> <86r5npun1e.fsf@blue.stonehenge.com> <3f1c29e71003130647x8e78411w82fcdde6f1f78479@mail.gmail.com> <4B9BD37E.1060801@infracaninophile.co.uk>
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On Sat, 13 Mar 2010 18:03:42 +0000 Matthew Seaman <m.seaman@infracaninophile.co.uk> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 >=20 > On 13/03/2010 14:47:31, =D0=90=D0=BD=D1=82=D0=BE=D0=BD =D0=9A=D0=BB=D0=B5= =D1=81=D1=81 wrote: > > I saw that more than year ago on my teacher's server, when I was > > deal with my first FreeBSD, so it's just a kind of habit. >=20 > It's a bad habit you should try and cure yourself of. Stepping the > clock with ntpdate(8) can cause nasty effects like time apparently > going backwards -- and that will seriously upset a lot of software. >=20 > Also, it doesn't account for the natural clock drift of your system, > so it's going to give you pretty terrible accuracy -- probably good > to no more than a few seconds. ntpdate(8) is really only intended to > get the clock into the right ballpark at system boot so that ntpd(8) > has a fighting chance of getting into synch. The NTP project has > deprecated ntpdate(8) for some time now, and instead prefers adding > an option to ntpd(8) to say "set the clock on initial startup no > matter how far out it is." >=20 > > But on the other hand, if it exists, it could work properly, and I > > am interested in just to understand, how it should be set up. >=20 > I'm assuming you're on some sort of always-on network, like ADSL? > Most people are nowadays. In which case, there's really no reason > not to run ntpd(8) the way it is intended to be used. >=20 > Just add the following to /etc/rc.conf: >=20 > ntpd_enable=3D"YES" > ntpd_sync_on_start=3D"YES" >=20 ntpd_sync_on_start=3D"YES" is not a complete substitute for running ntpdate at startup. It allows ntpd to make a large correction, but it doesn't block the boot sequence so you could still get a large step-change later-on when your daemons are starting-up.=20 ntpd has an option to emulate ntpdate, but it holds-up the boot-sequence much longer - presumably this is why ntpdate has been deprecated for a long time but hasn't yet gone away.=20 you can run ntpdate at boot with ntpdate_enable=3DYES the rc script gets the servers from ntp.conf
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