From owner-freebsd-questions@FreeBSD.ORG Wed Mar 15 14:28:04 2006 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 21EC716A401 for ; Wed, 15 Mar 2006 14:28:04 +0000 (UTC) (envelope-from xfb52@dial.pipex.com) Received: from asmtp-out6.blueyonder.co.uk (asmtp-out6.blueyonder.co.uk [195.188.213.65]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1D6E843D5A for ; Wed, 15 Mar 2006 14:28:02 +0000 (GMT) (envelope-from xfb52@dial.pipex.com) Received: from [80.192.2.135] (helo=[192.168.0.2]) by asmtp-out6.blueyonder.co.uk with esmtp (Exim 4.52) id 1FJWyn-0005Yl-4Z; Wed, 15 Mar 2006 14:28:01 +0000 Message-ID: <44182470.5060902@dial.pipex.com> Date: Wed, 15 Mar 2006 14:28:00 +0000 From: Alex Zbyslaw User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-GB; rv:1.7.12) Gecko/20060305 X-Accept-Language: en MIME-Version: 1.0 To: Jerry McAllister References: <200603151345.k2FDjY88027421@clunix.cl.msu.edu> In-Reply-To: <200603151345.k2FDjY88027421@clunix.cl.msu.edu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: dump level 9 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, 15 Mar 2006 14:28:04 -0000 Jerry McAllister wrote: >But, I wonder why you chose level 9 for your change dumps. It sort >of defeats the system. It would be more normal to use level 1. >I know that [some much] earlier versions of BSD dump only took levels >up to 5, but I presume that since they include up to 9 in the documentation >it should work. > > If you only use one level other than 0, then it makes no difference what that level is: 1, 9, 5 anything but 0. A level N dumps everything since the last dump < N, which in this case is always the last level 0. Using "modified tower of hanoi" (so the man page says :-)) can decrease the amount of data per dump at the cost of having to do more dumps: e.g. I do 0: 1 3 2 1 3 2 ... 0 ... But if I have to restore everything and the last dump was a 2, I have to restore the 0 1 and 2. Similarly if it crashed after 3, I would do 0 1 3. That cuts down the amount of data dumped, but is slightly more complex than just having to restore the 0 and last 9 (in the OPs case). I could use 1 7 9, or 4 6 8 instead of 1 2 3 and the data dumped would be the same in each case. I was pretty sure that BSD 4.2 had 9 incremental dump levels, but that was long, long ago in a universe of 1600bi tapes far, far away :-) --Alex