Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753188AbXHHEG3 (ORCPT ); Wed, 8 Aug 2007 00:06:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750734AbXHHEGS (ORCPT ); Wed, 8 Aug 2007 00:06:18 -0400 Received: from out2.smtp.messagingengine.com ([66.111.4.26]:36507 "EHLO out2.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750706AbXHHEGQ (ORCPT ); Wed, 8 Aug 2007 00:06:16 -0400 X-Sasl-enc: mkLH8xDRo5vDhHp/xlxNT1J51CDsuBHuznr6L72LwC41 1186545975 Date: Wed, 8 Aug 2007 01:06:07 -0300 From: Henrique de Moraes Holschuh To: Robert Hancock Cc: Tejun Heo , Michael Sedkowski , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, linux-acpi@vger.kernel.org Subject: Re: Disk spin down issue on shut down/suspend to disk Message-ID: <20070808040607.GA16466@khazad-dum.debian.net> References: <46B90AE0.2070403@shaw.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <46B90AE0.2070403@shaw.ca> X-GPG-Fingerprint: 1024D/1CDB0FE3 5422 5C61 F6B7 06FB 7E04 3738 EE25 DE3F 1CDB 0FE3 User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1767 Lines: 36 On Tue, 07 Aug 2007, Robert Hancock wrote: >> You *do* have to worry about it in any box you turn off daily. Desktop >> HDs will croak fast in that scenario, laptop HDs less so, but still too >> fast. A very good laptop HD can last about 20k emergency unloads (this >> is a unit that can do about 600k normal unloads in its lifetime). >> Desktop and server HDs don't even come close to those numbers, last time >> I checked. > > It only matters on hard drives which actually use load-unload heads. Lots > of desktop/server drives (perhaps some laptop ones as well) still use > contact start/stop, which doesn't remove the heads from the platters on I am not so sure about that. Please correct me if I am wrong, but contact stop in an emergency retract shakes the head assembly badly as well. It subjects the head assembly to higher acceleration than a normal seek, and a nasty impulse at impact with the stopper. And I very much doubt it is nice to the heads to slide into the parking zone at high speed and hit the bumper while over it. Unless I missed something, I don't why an emergency retract would not be as big a problem as an emergency unload. Maybe we should hunt down some proper datasheets for drives lacking head load/unload technology, and check what they say about emergency unloads... -- "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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/