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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!news.mel.connect.com.au!munnari.OZ.AU!news.ecn.uoknor.edu!feed1.news.erols.com!howland.erols.net!news.mathworks.com!fu-berlin.de!gusw.dialup.fu-berlin.DE!not-for-mail From: Gunther Schadow <gunther@gusw.dialup.fu-berlin.de> Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: dump and DAT, what block/density to use? Date: Fri, 29 Nov 1996 18:51:13 +0100 Organization: Freie Universitaet Berlin Lines: 31 Message-ID: <329F2291.2781E494@gusw.dialup.fu-berlin.de> References: <329E6BD7.5950@3-cities.com> NNTP-Posting-Host: gusw.dialup.fu-berlin.de (160.45.216.109) Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Access: 16 17 19 267 X-Mailer: Mozilla 3.0Gold (X11; I; FreeBSD 2.1.0-RELEASE i386) To: msmith@3-cities.com Mark Smith wrote: > I'm trying to use dump to backup a couple of file systems to a single > 2G DAT tape. The problem is that it gets about 300MB into a tape and > wants a new one. What block size and density options for dump should > I use to get the full 2G of tape? Yes, this is *very* awkward. I tried to guess the calcualtions of length capacity and density from the dump.c source code, but I don't understand the problems that are solved here. For me capacity is length * density and a byte is 8 bits, but what dump.c calculated there is obscure to me. Well, I gave up on this. And fortunately our fine DAT drive has enough capacity that thinking about it is not needed. Here are my dump commands: dump u0fbB /dev/nrst0 10 204810241024 don't care about the B option, it's just long enopugh to avoid dump calculate a capacity *smaller* than you actually have. Beware that for 10240 bytes per block you need to specify b 10 for dump, but b 20 for tar. BTW never use the erst device, since dump hangs trying to close the device when the tape is already offline. I always use nrst since I fill my tapes up using mt fsf/bsf seeking files back and forth. It's great! regards -- Gunther Schadow-----------Windsteiner Weg 54a, Berlin 14165, FR. Germany Dept. of Anaesthesia, Benjamin Franklin Univerity Hospital, Berlin. gusw@fub46.zedat.fu-berlin.de http://userpage.fu-berlin.de/~gusw ----------------------------------#include <usual/disclaimer>-----------