From owner-freebsd-questions@freebsd.org Wed Aug 31 16:35:40 2016 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 1A72DBCAA06 for ; Wed, 31 Aug 2016 16:35:40 +0000 (UTC) (envelope-from kuku@kukulies.org) Received: from kukulies.org (mail.kukulies.org [78.47.239.221]) by mx1.freebsd.org (Postfix) with ESMTP id D2446D9F for ; Wed, 31 Aug 2016 16:35:39 +0000 (UTC) (envelope-from kuku@kukulies.org) Received: from localhost (localhost [127.0.0.1]) by kukulies.org (Postfix) with ESMTP id 4238A4DA409 for ; Wed, 31 Aug 2016 18:35:31 +0200 (CEST) Received: from kukulies.org ([127.0.0.1]) by localhost (kukulies.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 38Y8GB_-qk6W for ; Wed, 31 Aug 2016 18:35:29 +0200 (CEST) Received: from [172.27.4.215] (unknown [87.79.34.228]) by kukulies.org (Postfix) with ESMTPSA id 55B9A4DA408 for ; Wed, 31 Aug 2016 18:35:29 +0200 (CEST) To: "freebsd-questions@freebsd.org" From: "Christoph P.U. Kukulies" Subject: dd blocksize when copying to SSD disk Message-ID: Date: Wed, 31 Aug 2016 18:35:28 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 31 Aug 2016 16:35:40 -0000 I'm about to copy an existing Windows 7 system to an SSD. Source drive is a hard disk of 256 GB, destination drive a 500 GB Samsung SSD 850 EVO. Given the fact that unnecessary write operations to SSDs should be avoided I'm thinking about the best strategy to use dd to write to the SSD. The disk has a capacity (from linux-fdisk): of 500.1 GB (500107862016 bytes) That's 976773168 sectors. It has reportedly 60801 cylinders ( 255 heads, 63 s/t gives 16065 sectors/cyl). When I calculate 976773168 / 60801 I'm getting 16065.0839... sectors / cyl - why this uneven number? Is there an incomplete track left over? After all, what would be the appropriate "bs"-parameter for the dd-command? What about socalled "alignment"? Help appreciated. -- Christoph