From owner-freebsd-questions@FreeBSD.ORG Thu May 15 19:18:58 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 2470F1065681 for ; Thu, 15 May 2008 19:18:58 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from mail-out3.apple.com (mail-out3.apple.com [17.254.13.22]) by mx1.freebsd.org (Postfix) with ESMTP id 0C7C88FC13 for ; Thu, 15 May 2008 19:18:58 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from relay14.apple.com (relay14.apple.com [17.128.113.52]) by mail-out3.apple.com (Postfix) with ESMTP id F11132BC0137; Thu, 15 May 2008 12:18:57 -0700 (PDT) Received: from relay14.apple.com (unknown [127.0.0.1]) by relay14.apple.com (Symantec Mail Security) with ESMTP id D7C602804C; Thu, 15 May 2008 12:18:57 -0700 (PDT) X-AuditID: 11807134-aaed1bb000000ed7-7e-482c8ca19c62 Received: from cswiger1.apple.com (cswiger1.apple.com [17.214.13.96]) by relay14.apple.com (Apple SCV relay) with ESMTP id BC7412803F; Thu, 15 May 2008 12:18:57 -0700 (PDT) Message-Id: <597571FB-C72D-4603-B379-A59A435843BE@mac.com> From: Chuck Swiger To: Volker Jahns In-Reply-To: <20080515185758.GA12709@ikarus.thalreit> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v919.2) Date: Thu, 15 May 2008 12:18:57 -0700 References: <20080515185758.GA12709@ikarus.thalreit> X-Mailer: Apple Mail (2.919.2) X-Brightmail-Tracker: AAAAAA== Cc: freebsd-questions@freebsd.org 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 19:18:58 -0000 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. 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... Regards, -- -Chuck