Date: Thu, 15 May 2008 16:08:19 -0500 From: David Kelly <dkelly@hiwaay.net> To: Volker Jahns <volker@thalreit.de> Cc: freebsd-questions@freebsd.org Subject: Re: time drift Message-ID: <20080515210819.GA12605@Grumpy.DynDNS.org> In-Reply-To: <20080515185758.GA12709@ikarus.thalreit> References: <20080515185758.GA12709@ikarus.thalreit>
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On Thu, May 15, 2008 at 08:57:59PM +0200, Volker Jahns wrote: > FreeBSD 6.2 running on X86 hardware (FSC) shows a remarkable time > drift > > running ntpdate every half hour shows that the system looses about 10-14 sec each time. > 15 May 10:06:48 ntpdate[7200]: step time server 192.53.103.108 offset -13.799602 sec > 15 May 10:36:48 ntpdate[7515]: step time server 192.53.103.108 offset -12.813941 sec > 15 May 11:06:48 ntpdate[7879]: step time server 192.53.103.108 offset -13.651921 sec > 15 May 11:36:50 ntpdate[8079]: step time server 192.53.103.108 offset -11.109298 sec > 15 May 12:06:50 ntpdate[8289]: step time server 192.53.103.108 offset -11.836499 sec [...] > What would be your suspicion on the large time drift of the FreeBSD > 6.2 system? Its PC commodity-grade. Not all that unusual even for stuff sold claiming to be a "server". This is in no small part why ntpd exists. nptd calculates a correction coefficient and (under FreeBSD) stores it in /var/db/ntpd.drift for use on next start so as to more quickly establish a lock. So in short ntpd calibrates your clock in order to minimize the corrections required. Is The Right Thing To Do. -- David Kelly N4HHE, dkelly@HiWAAY.net ======================================================================== Whom computers would destroy, they must first drive mad.
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