From owner-freebsd-questions@FreeBSD.ORG Sun May 25 09:43:21 2003 Return-Path: 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 6E47C37B401 for ; Sun, 25 May 2003 09:43:21 -0700 (PDT) Received: from out001.verizon.net (out001pub.verizon.net [206.46.170.140]) by mx1.FreeBSD.org (Postfix) with ESMTP id 9C87843F75 for ; Sun, 25 May 2003 09:43:20 -0700 (PDT) (envelope-from cswiger@mac.com) Received: from mac.com ([129.44.60.214]) by out001.verizon.net (InterMail vM.5.01.05.33 201-253-122-126-133-20030313) with ESMTP id <20030525164320.FSU12592.out001.verizon.net@mac.com>; Sun, 25 May 2003 11:43:20 -0500 Message-ID: <3ED0F2A4.8050107@mac.com> Date: Sun, 25 May 2003 12:43:16 -0400 From: Chuck Swiger Organization: The Courts of Chaos User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4b) Gecko/20030507 X-Accept-Language: en-us, en MIME-Version: 1.0 To: D Velez References: <3ED0E9B0.4060703@verizon.net> In-Reply-To: <3ED0E9B0.4060703@verizon.net> X-Enigmail-Version: 0.75.0.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Authentication-Info: Submitted using SMTP AUTH at out001.verizon.net from [129.44.60.214] at Sun, 25 May 2003 11:43:19 -0500 cc: questions@freebsd.org Subject: Re: using dd to copy my freebsd partion to another drive X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 25 May 2003 16:43:21 -0000 D Velez wrote: [ ...] > but all have different block sizes and I am confuse. I see some as > bs=512 bs=1024 bs=8192, etc.... > > Is there a way to calculate the block size of the > two hard drives myself or is there a standard > block size to use for any hard drive, cdrom and floppy. Many devices actually have physical 512-byte sectors (not CD's and DVD's though), so 512 is the closest thing to a "standard" block size. People commonly use larger block sizes because multi-sector reads go faster in most circumstances. Try comparing bs=512 and bs=5120 and see for yourself. Also, note that dd is best used when the source and destination are identical: if your other drive is a different size, you might find using dump and restore to be a better bet. -Chuck