From owner-freebsd-questions@FreeBSD.ORG Wed Nov 16 18:30:09 2005 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5740E16A41F for ; Wed, 16 Nov 2005 18:30:09 +0000 (GMT) (envelope-from jonc@chen.org.nz) Received: from chen.org.nz (chen.org.nz [210.54.19.51]) by mx1.FreeBSD.org (Postfix) with ESMTP id DAD6A43D45 for ; Wed, 16 Nov 2005 18:30:08 +0000 (GMT) (envelope-from jonc@chen.org.nz) Received: by chen.org.nz (Postfix, from userid 1000) id AD94956425; Thu, 17 Nov 2005 07:30:06 +1300 (NZDT) Date: Thu, 17 Nov 2005 07:30:06 +1300 From: Jonathan Chen To: Chuck Swiger Message-ID: <20051116183006.GB2539@osiris.chen.org.nz> References: <20051115214101.fb30f4fa.dick@nagual.st> <20051116162615.0a3b7707.dick@nagual.st> <437B67D9.50108@mac.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <437B67D9.50108@mac.com> User-Agent: Mutt/1.4.2.1i Cc: "Andrew P." , fbsdq Subject: Re: ntpdate 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: Wed, 16 Nov 2005 18:30:09 -0000 On Wed, Nov 16, 2005 at 12:09:45PM -0500, Chuck Swiger wrote: [...] > Running "ntpdate -b" at boot to forcibly syncronize the clock is a pretty > good idea, but you actually can convince ntpd to sync even a clock which is > badly off via: > > -g Normally, ntpd exits if the offset exceeds the sanity limit, > which is 1000 s by default. If the sanity limit is set to > zero, > no sanity checking is performed and any offset is acceptable. > This option overrides the limit and allows the time to be set > to > any value without restriction; however, this can happen only > once. After that, ntpd will exit if the limit is exceeded. > This > option can be used with the -q option. The advantage of `ntpdate' vs `ntpd -g' is that ntpdate does it _immediately_, whereas `ntpd -g' takes a bit of time before it decides which server to sync to. This means that if your clock is out by hours/days, there will be a period of 3-7 minutes after you boot where your system time is badly incorrect, and then you have this big skip when it corrects. This could be a problem if you've got overanxious users running `make' and other time sensitive programs almost immediately after boot; not to mention weird skips in your various log files. Cheers. -- Jonathan Chen ---------------------------------------------------------------------- "If everything's under control, you're going too slow" - Mario Andretti