From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1P1MLt-0001Do-G2 for garchives@archives.gentoo.org; Thu, 30 Sep 2010 16:51:25 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id E21BDE09B7; Thu, 30 Sep 2010 16:51:01 +0000 (UTC) Received: from out5.smtp.messagingengine.com (out5.smtp.messagingengine.com [66.111.4.29]) by pigeon.gentoo.org (Postfix) with ESMTP id B690BE09B7 for ; Thu, 30 Sep 2010 16:51:01 +0000 (UTC) Received: from compute3.internal (compute3.nyi.mail.srv.osa [10.202.2.43]) by gateway1.messagingengine.com (Postfix) with ESMTP id 97B5168E; Thu, 30 Sep 2010 12:51:01 -0400 (EDT) Received: from frontend2.messagingengine.com ([10.202.2.161]) by compute3.internal (MEProxy); Thu, 30 Sep 2010 12:51:01 -0400 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=messagingengine.com; h=message-id:date:from:reply-to:mime-version:to:subject:references:in-reply-to:content-type; s=smtpout; bh=XKmnu2Xnm+DSYlcDudjJp+pEr68=; b=POondf7V/l10O8TYbPPxegXc0MnuOW1jyvoS6fBpPRsgFmNgLpkz+EZjsIoac4b1GbkIs9VXFOLaUox+2++KkqK5Ck4wL6U65h2GS7TNBlj5gd+GMHj+E3aCmc1Sc2JSRXWmGNUlKmYC+XuLFh/1DXOE7D/NHgRQ38IFfr3bNpk= X-Sasl-enc: FOIUe3CSiFAABZz9QUgsUtV79flmwytcFVwnNrhmOSZq 1285865460 Received: from [192.168.5.18] (lvps83-169-5-6.dedicated.hosteurope.de [83.169.5.6]) by mail.messagingengine.com (Postfix) with ESMTPSA id 0F6E65E46B0 for ; Thu, 30 Sep 2010 12:50:59 -0400 (EDT) Message-ID: <4CA4BFE1.1050804@f_philipp.fastmail.net> Date: Thu, 30 Sep 2010 18:50:41 +0200 From: Florian Philipp User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100927 Lightning/1.0b3pre Thunderbird/3.1.4 Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] Normal disk speed? References: <201009301510.43043.lists@f_philipp.fastmail.net> <201009301700.17007.peter@humphrey.ukfsn.org> In-Reply-To: <201009301700.17007.peter@humphrey.ukfsn.org> X-Enigmail-Version: 1.1.2 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigB8C2D13FEB397B9FA97FED21" X-Archives-Salt: 22824200-ab5f-4084-b625-2009c4ea7205 X-Archives-Hash: 4630f8b1cdadf374f40aeef6947438c2 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigB8C2D13FEB397B9FA97FED21 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Am 30.09.2010 18:00, schrieb Peter Humphrey: > On Thursday 30 September 2010 14:10:42 Florian Philipp wrote: >=20 >> An HDD gets slower when you read the inner tracks. The angular >> velocity is constant (5400 RPM) while the tangential velocity gets >> lower with the radius. >=20 > Are you telling us that the length of a stored bit is constant? I'd hav= e=20 > thought it was the time needed to read or write a bit that was constant= ;=20 > otherwise the electronics would get extremely complex. In that case it'= s=20 > the angular velocity that counts, not the linear velocity, and it=20 > matters not which track your data are on. (If a block goes past the hea= d=20 > twice as fast, it also occupies twice the space, so you're back where=20 > you were.) Yes, the length of a block is constant. If the innermost "ring" (track) contains 4 blocks, the next ring contains maybe 5 blocks.[1] Put another way: If you could pack your bits more densely on innermost tracks, why wouldn't you pack them that densely on the whole disk and thereby increase the overall capacity? >=20 > That's the way it was with our imposing new 2MB disks in 1974, anyway. = > They occupied boxes four feet tall and six feet long, and had external = > air systems; I was one of those responsible for the maintenance; we wer= e=20 > sent on a training course specifically for the disks. I can't remember = > who made them, but they were part of a Ferranti Argus 500 system at the= =20 > then national grid control centre. >=20 > Maybe technology has changed since then. >=20 Well, we are talking about devices employing the GMR effect while also doing error correction and remapping of defect sectors on-the-fly. I guess a little lookup table from track number to time-per-block doesn't add too much complexity. You can easily test this if you have various partitions on your HDD. Just compare dd throughput for your first partition versus your last one.= [1] The numbers are arbitrary. The number increases linearly. C =3D 2*pi*= r --------------enigB8C2D13FEB397B9FA97FED21 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkykv+gACgkQqs4uOUlOuU82MACfQoc2Y+08r5V79vRcIohTcaBN CiIAnjManDAneS9ep+aVk673v7vLC2d7 =VcME -----END PGP SIGNATURE----- --------------enigB8C2D13FEB397B9FA97FED21--