Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934102AbXHHE1w (ORCPT ); Wed, 8 Aug 2007 00:27:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752161AbXHHE1n (ORCPT ); Wed, 8 Aug 2007 00:27:43 -0400 Received: from shawidc-mo1.cg.shawcable.net ([24.71.223.10]:31437 "EHLO pd3mo1so.prod.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751165AbXHHE1l (ORCPT ); Wed, 8 Aug 2007 00:27:41 -0400 Date: Tue, 07 Aug 2007 22:26:46 -0600 From: Robert Hancock Subject: Re: Disk spin down issue on shut down/suspend to disk In-reply-to: <20070808040607.GA16466@khazad-dum.debian.net> To: Henrique de Moraes Holschuh Cc: Tejun Heo , Michael Sedkowski , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, linux-acpi@vger.kernel.org Message-id: <46B94606.9040003@shaw.ca> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit References: <46B90AE0.2070403@shaw.ca> <20070808040607.GA16466@khazad-dum.debian.net> User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2384 Lines: 47 Henrique de Moraes Holschuh wrote: > 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... I did a bit of a look and didn't find any mention of the subject for drives using contact start/stop. I did find mention that the unload torque needed is quite a bit higher on load/unload systems, so I would imagine that having to extract or store that energy for emergency unloads would be more of a demanding task and might be a rougher process. Just judging from the sound, though, hard power-offs on a desktop Seagate Barracuda 7200.10, for example, which is contact start/stop, don't really sound any different from a commanded standby. On the laptop drives I've seen you can really tell the difference. -- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/ - 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/