From owner-freebsd-questions@FreeBSD.ORG Thu May 15 21:08:23 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D8AD01065677 for ; Thu, 15 May 2008 21:08:23 +0000 (UTC) (envelope-from dkelly@Grumpy.DynDNS.org) Received: from smtp.knology.net (smtp.knology.net [24.214.63.101]) by mx1.freebsd.org (Postfix) with ESMTP id 3DCB28FC38 for ; Thu, 15 May 2008 21:08:22 +0000 (UTC) (envelope-from dkelly@Grumpy.DynDNS.org) Received: (qmail 2897 invoked by uid 0); 15 May 2008 21:08:20 -0000 Received: from unknown (HELO Grumpy.DynDNS.org) (216.186.148.249) by smtp1.knology.net with SMTP; 15 May 2008 21:08:20 -0000 Received: by Grumpy.DynDNS.org (Postfix, from userid 928) id AA24B28429; Thu, 15 May 2008 16:08:19 -0500 (CDT) Date: Thu, 15 May 2008 16:08:19 -0500 From: David Kelly To: Volker Jahns Message-ID: <20080515210819.GA12605@Grumpy.DynDNS.org> References: <20080515185758.GA12709@ikarus.thalreit> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080515185758.GA12709@ikarus.thalreit> User-Agent: Mutt/1.4.2.3i Cc: freebsd-questions@freebsd.org Subject: Re: time drift X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: FreeBSD-Questions@FreeBSD.org List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 May 2008 21:08:23 -0000 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.