From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robert Hancock Subject: Re: Disk spin down issue on shut down/suspend to disk Date: Tue, 07 Aug 2007 18:14:24 -0600 Message-ID: <46B90AE0.2070403@shaw.ca> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-reply-to: Sender: linux-acpi-owner@vger.kernel.org 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 List-Id: linux-ide@vger.kernel.org Henrique de Moraes Holschuh wrote: > On Tue, 07 Aug 2007, Tejun Heo wrote: >> emergency unload. Emergency unload does shorten the lifespan of the >> disk but you don't have to worry too much about it. Disks are designed >> to withstand certain number of emergency unloads. > > 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 shutdown but just parks the heads over the landing zone. I don't think arbitrary power-offs make too much difference on those drives. (However, these generally aren't rated to handle as many start/stop cycles, which is why laptop drives generally use load/unload instead.) -- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/