Date: Fri, 7 Jun 2019 16:43:29 +0200 From: Per Hedeland <per@hedeland.org> To: freebsd-questions@freebsd.org Subject: Re: ntpd configutration -- a small suggestion from the peanut gallery Message-ID: <344cca54-6005-7b0c-703a-5a11827a6a8d@hedeland.org> In-Reply-To: <2ac65d8d-731e-45f6-18ba-c215704b32d9@qeng-ho.org> References: <48793.1559715528@segfault.tristatelogic.com> <alpine.BSF.2.21.9999.1906050834470.5734@enterprise.ximalas.info> <20190606171120.29f7fd85@gumby.homeunix.com> <37c862b6-f623-4210-9c77-c404e31f4808@www.fastmail.com> <2ac65d8d-731e-45f6-18ba-c215704b32d9@qeng-ho.org>
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On 2019-06-07 16:04, Arthur Chance wrote: > On 07/06/2019 09:57, Dave Cottlehuber wrote: >> On Thu, 6 Jun 2019, at 18:14, RW via freebsd-questions wrote: >>> On Wed, 5 Jun 2019 08:40:51 +0200 (CEST) >>> Trond Endrestøl wrote: >>> >>>> On Tue, 4 Jun 2019 23:18-0700, Ronald F. Guilmette wrote: >>>> >>>>> I feel sure that I'll be able to figure out how to get ntpd properly >>>>> enabled & configured, but I would just like to offer, hunbly, to the >>>>> Powers That Be, that it would be Nice if ntpd, once enabled during >>>>> install, just worked, you know, right outta the box. >>>> >>>> Adding >>>> >>>> ntpd_sync_on_start="YES" >>>> >>>> to /etc/rc.conf is one way. >>> >>> Perhaps it should be the default. >> >> It is in CURRENT[1] & would be worth MFC although possibly too late >> for 11.3R. >> >> https://www.freebsd.org/cgi/man.cgi?query=ntpdate mentions: >> >> DESCRIPTION >> Note: The functionality o this program is now available in the ntpd(8) >> program. See the -q command line option in the ntpd(8) page. After a >> suitable period of mourning, the ntpdate utility is to be retired from >> this distribution. >> >> Perhaps a revision that uses ntpd_flags would be better? > > There is one advantage to using ntpdate_enable="YES" rather than > ntpd_sync_on_start="YES" and that's the fact that ntpdate is blocking. > When the rc script finishes you know the clock is correct, whereas with > ntpd_sync_on_start the time step can be some time after the script has > returned. If you run a daemon like dovecot that objects to time going > backwards (and dies) that can be a problem. Yes, this is a very big advantage - it can take a *very* long time for ntpd to get the clock correct, with or without the -g option a.k.a. ntpd_sync_on_start, and there is no straightforward way to find out when it has happened. But in fact the reference implementation folks do not suggest that 'ntpd -g' can be a replacement for ntpdate - as you can see in the ntpdate man page excerpt above, it points to the *-q* option to ntpd. This option is not something you can put in ntpd_flags though, see the ntpd man page - i.e. the idea is that you run 'ntpd -q', which is blocking, and "pretty fast", instead of ntpdate, and when it completes you start the ntpd daemon with whatever *other* flags you want (-g can still make sense there, in case the 'ntpd -q' failed somehow). However ntpdate is still typically significantly faster than 'ntpd -q', and in case ntpdate ever gets removed from the reference distribution (it's still present in the latest version of their development branch), I would actually hope that FreeBSD retains it and continues to make it available as an rc.conf option. --Per >> --panicgate >> >> [2]: https://www.freebsd.org/cgi/man.cgi?query=ntpd >> [1]: https://svnweb.freebsd.org/base?view=revision&revision=r326095 >> >> Author: manu <manu@FreeBSD.org> >> Date: Wed Nov 22 15:27:47 2017 +0000 >> >> bsdinstall: Add ntpdate option >> >> When you install a computer for the first time, the date in the CMOS sometimes >> not accurate and you need to ntpdate as ntpd will fail a the time difference >> is too big. >> Add an option in bsdinstall to enable ntpdate that will do that for us. >> >> Reviewed by: allanjude >> Differential Revision: https://reviews.freebsd.org/D13149 >> > >
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