From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933195AbWKNDoF (ORCPT ); Mon, 13 Nov 2006 22:44:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933179AbWKNDoF (ORCPT ); Mon, 13 Nov 2006 22:44:05 -0500 Received: from out1.smtp.messagingengine.com ([66.111.4.25]:49889 "EHLO out1.smtp.messagingengine.com") by vger.kernel.org with ESMTP id S933195AbWKNDoC (ORCPT ); Mon, 13 Nov 2006 22:44:02 -0500 X-Sasl-enc: wRJdumkdnyAsFfuD2r4a2f47/O5ZhOsr7fCz6TUz97V3 1163475842 Date: Tue, 14 Nov 2006 01:43:55 -0200 From: Henrique de Moraes Holschuh To: Pavel Machek Cc: Mark Lord , Jeff Garzik , Andi Kleen , John Fremlin , kernel list , htejun@gmail.com, jim.kardach@intel.com Subject: HD head unloads (was: Re: AHCI power saving) Message-ID: <20061114034355.GB5810@khazad-dum.debian.net> References: <87k639u55l.fsf-genuine-vii@john.fremlin.org> <20061113142219.GA2703@elf.ucw.cz> <45589008.1080001@garzik.org> <200611131637.56737.ak@suse.de> <455893E5.4010001@garzik.org> <4558B232.8080600@rtr.ca> <20061113220127.GA1704@elf.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061113220127.GA1704@elf.ucw.cz> X-GPG-Fingerprint: 1024D/1CDB0FE3 5422 5C61 F6B7 06FB 7E04 3738 EE25 DE3F 1CDB 0FE3 User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 13 Nov 2006, Pavel Machek wrote: > On Mon 2006-11-13 12:58:10, Mark Lord wrote: > > Jeff Garzik wrote: > > >Andi Kleen wrote: > > > > > >>How does it shorten its life? > > > > > >Parks your hard drive heads many thousands of times more often than it > > >does without the aggressive PM features. > > > > Spinning-down would definitely shorten the drive lifespan. Does it do that? > > Not on my machine. Heck, given just how much a ThinkPad T43 BIOS will attempt to do it for you, consider yourself lucky if the X60 behaves differently. When I thought of monitoring the head unload counter through SMART on mine, my HD was already beyond 14k unloads... and the notebook had been powered up less than 100 times :p The BIOS likes to set the drive APM mode to something other than "off", and in many drives (well, Hitachi ones at least), that means the drive will be happy to unload heads every chance it gets, so as to be able to power off the head assembly motion drive. > > Parking heads is more like just doing some extra (long) seeks. Long seeks don't lift the head assembly off the plates, head unloads do. And head unloads will also power down some stuff in laptop HDs, seeks don't do that either. And even old-style parking places the heads on a different surface than the data area. That's a lot different from seeks no matter how one looks at it. > > Is this documented somewhere as being a life-shortening action? Yes, although not often with that many words. For example, a Hitachi Travelstar 5k100 is rated for 600k load/unload cycles, and 20k emergency load/unload cycles (each emergency unload counts as 30 normal unloads, but the tech docs say it is about 100 times more stressfull to the drive). It is in the public drive datasheet, along with other important information, such as that the drive needs to spin down often (no less than once every 48h) or its lifespan will be shortened. A typical desktop HD can probably survive a lot less head load/unload cycles and spin up/down cycles than that. -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh