From owner-freebsd-ports@FreeBSD.ORG Fri Jan 17 21:22:39 2014 Return-Path: Delivered-To: ports@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 4F1D1C06 for ; Fri, 17 Jan 2014 21:22:39 +0000 (UTC) Received: from mail-ie0-x235.google.com (mail-ie0-x235.google.com [IPv6:2607:f8b0:4001:c03::235]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 1BDF61CFC for ; Fri, 17 Jan 2014 21:22:39 +0000 (UTC) Received: by mail-ie0-f181.google.com with SMTP id tq11so4216713ieb.12 for ; Fri, 17 Jan 2014 13:22:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=p6SXRJ2Nujk5EbJqfo4uW3kcOhB2/sT92cvnj38ZWYs=; b=zv8n+rZpdBLP0qbkKvHIc4ICol/1B8wmuHjINqrdtHdv/JFpIzpcwAVrsscwV5Z/As U0hK5PAd1YY/PYU7rDqB2J7KjK4zoKPqAPC/yuGUpC1gYRC1TpeKDh2ISWvWafJQxkxW ZpiUmuzvoF2DwtFEi289QCNCyFXrQZhkkzD1Gm+RjBv/PmAqFFypHFJHmfsD7V99Yn4j okC8DPm8NxgFXwI5IqAObYAc0Wt7UCFUp2bxwGGqemQAzfOA+7goFCDkQGjL2vaDV3bZ 1T9dzeqrsStTES59V5eNpGO74z2mjrDqPPnum2NhQuNmsnEbk3aEvCizrhtxavajNl4B UzzQ== MIME-Version: 1.0 X-Received: by 10.50.29.49 with SMTP id g17mr401677igh.35.1389993758559; Fri, 17 Jan 2014 13:22:38 -0800 (PST) Received: by 10.64.33.12 with HTTP; Fri, 17 Jan 2014 13:22:38 -0800 (PST) In-Reply-To: References: Date: Fri, 17 Jan 2014 13:22:38 -0800 Message-ID: Subject: Re: clonehdd followup From: paul beard To: Kevin Oberman Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.17 Cc: FreeBSD Ports , bart@tapolsky.net.ua X-BeenThere: freebsd-ports@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Porting software to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 17 Jan 2014 21:22:39 -0000 On Fri, Jan 17, 2014 at 1:17 PM, Kevin Oberman wrote: > Remember that 1.5GB/s is the speed supported by the electronics and the > cache. It is not the speed that the disk actually reads or writes from/to > the platters. When cloning, very little of the data is in cache, so you are > generally limited by seek times (should be minimal if the code is well > done) and rotational speed. The really then boils down to transfer speeds > are going ot be close to what is possible with the rotational speed. > Yeah, I knew 1.5G was our old friend, the theoretical maximum, or his cousin, the optimal transfer rate. I was hoping for something better than 500M/minute. I'm sure there are any number of factors that are slowing things down. It seemed like incorporating the larger blocks/boundary alignment might help. I'm testing it now and I'm not sure I'm seeing it. -- Paul Beard / www.paulbeard.org/