Date: Tue, 4 May 2021 09:58:41 -0400 From: Paul Mather <paul@gromit.dlib.vt.edu> To: bob prohaska <fbsd@www.zefox.net> Cc: tech-lists <tech-lists@zyxst.net>, freebsd-arm@freebsd.org Subject: Re: Timezone problems on -current Message-ID: <F93D8E92-C307-4799-8F6B-572D8184DD1A@gromit.dlib.vt.edu> In-Reply-To: <20210504042024.GA42279@www.zefox.net> References: <20210503153442.GB37236@www.zefox.net> <YJCf00lvkp%2BUyamn@cloud.zyxst.net> <20210504015222.GE37236@www.zefox.net> <YJDB0KEogTC1hWkF@ceres.zyxst.net> <20210504042024.GA42279@www.zefox.net>
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On May 4, 2021, at 12:20 AM, bob prohaska <fbsd@www.zefox.net> wrote: > On Tue, May 04, 2021 at 04:38:56AM +0100, tech-lists wrote: >> On Mon, May 03, 2021 at 06:52:22PM -0700, bob prohaska wrote: >>=20 >>> Up to now I've used only the line >>> ntpdate_enable=3D"YES" >>=20 >> Seems ntpdate isn't required if these are set in /etc/rc.conf >>=20 >> ntpd_enable=3D"YES" >> ntpd_sync_on_start=3D"YES" >>=20 >> even on boards with no RTC. >=20 > Indeed it looks as if ntpdate is going away, replaced by > enhancements to ntpd.=20 >=20 > Still, I think the timekeeping errors are caused by a somewhat > unconventional network setup on the machine having problems. > The rest of the hosts in my "data center" use ntpdate and=20 > have no trouble keeping their clocks right, but those hosts > all have wired ethernet. The host with the wrong clock setting > uses an ethernet-to-wifi adapter. Can't be sure until more=20 > testing is done. And, I might be wrong again..... The problem with ntpdate is that it is a one-time clock adjustment = whereas ntpd is a continuous time monitoring/adjustment. So, if your = system has problems with clock drift or just keeping accurate time, = ntpdate run on boot will not help in the long term. Ntpd, on the other = hand, will. Note also that 'ntpd_sync_on_start=3D"YES"' is effectively the same as = running ntpddate. The 'ntpd_sync_on_start=3D"YES"' setting lets ntpd = perform a one-time large step time adjustment (via the "-g" option), = which is essentially what you are achieving when running ntpdate. = Normally, ntpd will baulk if the clock is off by 1000s, which can easily = happen with systems that have no RTC, hence the need for the = 'ntpd_sync_on_start=3D"YES"' flag. When I ran FreeBSD/arm, I used the net/ntimed port to maintain time, = which is a simple, low-resource alternative to ntpd for keeping time on = FreeBSD/arm clients. Cheers, Paul.
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