From owner-freebsd-questions@FreeBSD.ORG Fri Dec 21 18:44:45 2007 Return-Path: Delivered-To: questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6E34616A41A for ; Fri, 21 Dec 2007 18:44:45 +0000 (UTC) (envelope-from SRS0=04527191878c7d9dce7039eb1c1e2f91e0593f8b=556=es.net=webster@es.net) Received: from postal1.es.net (postal4.es.net [IPv6:2001:400:6000:1::66]) by mx1.freebsd.org (Postfix) with ESMTP id 92A6B13C458 for ; Fri, 21 Dec 2007 18:44:44 +0000 (UTC) (envelope-from SRS0=04527191878c7d9dce7039eb1c1e2f91e0593f8b=556=es.net=webster@es.net) Received: from vortex.es.net (vortex.es.net [198.128.1.16]) by postal4.es.net (Postal Node 4) with ASMTP (SSL) id AEN37943; Fri, 21 Dec 2007 10:44:43 -0800 Date: Fri, 21 Dec 2007 10:44:42 -0800 From: John Webster To: Bill Moran Message-ID: <62F8888810A130657FBCAF47@vortex.es.net> In-Reply-To: <20071221132440.31ded74f.wmoran@potentialtech.com> References: <20071218165521.GA37529@bewilderbeast.blackhelicopters.org> <343753.78466.qm@web44811.mail.sp1.yahoo.com> <20071221112303.19619c39.wmoran@potentialtech.com> <7BEE288E7C218E96DB9E8AA0@jw-laptop.dhcp.lbnl.us> <20071221132440.31ded74f.wmoran@potentialtech.com> X-Mailer: Mulberry/3.1.6 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Sender-IP: 198.128.1.16 X-Sender-Domain: es.net X-Recipent: ; ; ; ; X-Sender: X-To_Name: Bill Moran X-To_Domain: potentialtech.com X-To: Bill Moran X-To_Email: wmoran@potentialtech.com X-To_Alias: wmoran Cc: questions@freebsd.org, "Michael W. Lucas" , shinny knight Subject: Re: timekeeping on jail servers X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: John Webster List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 21 Dec 2007 18:44:45 -0000 --On Friday, December 21, 2007 13:24:40 -0500 Bill Moran wrote: > In response to John Webster : >> >> --On December 21, 2007 11:23:03 AM -0500 Bill Moran wrote: >> >> > In response to shinny knight : >> > >> > The reason that is not recommended is that it results in sudden steps >> > of the clock. Occasionally, these steps go backwards. Software that >> > is very sensitive to time changes (make processes, database servers, >> > anything doing calculations WRT time) can break, crash, or work >> > inaccurately. >> >> ntpdate -B should slew the time slowly. (According to the manpage.) > > Not generally suitable for cron because it can take longer to slew > than it does for the next cron execution to occur, which would then > result in multiple ntpdate programs fighting each other (not sure > what the effect of this would be). > If I were doing it I would write a script with locking in order to ensure multiple jobs don't fight. Simple. Happy Holidays!