From owner-freebsd-questions@FreeBSD.ORG Sat Nov 21 00:52:34 2009 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 413E81065676 for ; Sat, 21 Nov 2009 00:52:34 +0000 (UTC) (envelope-from freebsd@edvax.de) Received: from mx02.qsc.de (mx02.qsc.de [213.148.130.14]) by mx1.freebsd.org (Postfix) with ESMTP id F324E8FC14 for ; Sat, 21 Nov 2009 00:52:33 +0000 (UTC) Received: from r55.edvax.de (port-92-195-114-224.dynamic.qsc.de [92.195.114.224]) by mx02.qsc.de (Postfix) with ESMTP id DF05B1E30D; Sat, 21 Nov 2009 01:52:31 +0100 (CET) Received: from r55.edvax.de (localhost [127.0.0.1]) by r55.edvax.de (8.14.2/8.14.2) with SMTP id nAL0qUwK002253; Sat, 21 Nov 2009 01:52:31 +0100 (CET) (envelope-from freebsd@edvax.de) Date: Sat, 21 Nov 2009 01:52:30 +0100 From: Polytropon To: "Ronald F. Guilmette" Message-Id: <20091121015230.cf2c15dd.freebsd@edvax.de> In-Reply-To: <7972.1258760914@tristatelogic.com> References: <7872.1258759936@tristatelogic.com> <7972.1258760914@tristatelogic.com> Organization: EDVAX X-Mailer: Sylpheed 2.4.7 (GTK+ 2.12.1; i386-portbld-freebsd7.0) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: BTX Loader crashes -- Help wanted X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Polytropon List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 21 Nov 2009 00:52:34 -0000 On Fri, 20 Nov 2009 15:48:34 -0800, "Ronald F. Guilmette" wrote: > But I have one question. The author sez to do this: > > dd if=8.0-BETA1-amd64-memstick.img of=/dev/da0 bs=10240 conv=sync > > I just want to know what the effect of conv=sync and why it might be > necessary. According to "man dd": bs=n Set both input and output block size to n bytes, superseding the ibs and obs operands. If no conversion values other than noerror, notrunc or sync are specified, then each input block is copied to the output as a single block without any aggregation of short blocks. in conjunction with conv=value[,value ...] Where value is one of the symbols from the following list. sync Pad every input block to the input buffer size. Spaces are used for pad bytes if a block oriented conversion value is specified, otherwise NUL bytes are used. it appears that the data is ensured to be "properly aligned" with a possibly different block size on the source or target media. As far as I remember, not giving the bs= argument would result in a default block size of 512 bytes which may - but don't ask me why - lead to a non-functioning target USB stick. -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ...