From owner-freebsd-questions@FreeBSD.ORG Thu May 15 19:52:59 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 AB3B71065674 for ; Thu, 15 May 2008 19:52:59 +0000 (UTC) (envelope-from volker@thalreit.de) Received: from moutng.kundenserver.de (moutng.kundenserver.de [212.227.126.171]) by mx1.freebsd.org (Postfix) with ESMTP id 43DA48FC29 for ; Thu, 15 May 2008 19:52:59 +0000 (UTC) (envelope-from volker@thalreit.de) Received: from thalreit.de (p5496D19C.dip.t-dialin.net [84.150.209.156]) by mrelayeu.kundenserver.de (node=mrelayeu7) with ESMTP (Nemesis) id 0ML2xA-1JwjVa0KmW-0005Rp; Thu, 15 May 2008 21:52:58 +0200 Received: from localhost ([127.0.0.1] helo=ikarus.thalreit) by thalreit.de with esmtp (Exim 4.63 (FreeBSD)) (envelope-from ) id 1JwjVf-0003XN-BZ; Thu, 15 May 2008 21:53:03 +0200 Received: (from volker@localhost) by ikarus.thalreit (8.13.6/8.13.6/Submit) id m4FJr3mD013600; Thu, 15 May 2008 21:53:03 +0200 (CEST) (envelope-from volker) Date: Thu, 15 May 2008 21:53:02 +0200 From: Volker Jahns To: Chuck Swiger Message-ID: <20080515195302.GA13531@ikarus.thalreit> References: <20080515185758.GA12709@ikarus.thalreit> <597571FB-C72D-4603-B379-A59A435843BE@mac.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <597571FB-C72D-4603-B379-A59A435843BE@mac.com> User-Agent: Mutt/1.4.2.3i X-Provags-ID: V01U2FsdGVkX1+Whp3bW/QeuRP1oq7qVrr0Z2UXjEhHE7t1SHm xh2IIir9VOEEposb3w6Jo/KVaJ64Ve2vmvyb3YrekLyTiNsGvu GObUT3roR//aXstfZwwhw== Cc: freebsd-questions@freebsd.org, Volker Jahns Subject: Re: time drift X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 May 2008 19:52:59 -0000 On Thu, May 15, 2008 at 12:18:57PM -0700, Chuck Swiger wrote: > On May 15, 2008, at 11:57 AM, 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 > > While you should run ntpdate -b at system boot, running ntpdate > periodically via cron is not the right thing to do-- you should run > ntpd instead, and that will figure out the intrinsic correction your > chosen system clock needs to keep better time via the ntp.drift file. Running ntpd on this system results in time drift of approx. 1-2 hrs a day. That is not an acceptable option. > > You should also take a look at the output of "sysctl > kern.timecounter", and possibly switch to a different mechanism, if > the existing choice doesn't work out well for your machine... Thanks for the hint. -- Volker Jahns, volker@thalreit.de