linux-kernel - Re: Disk spin down issue on shut down/suspend to disk

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Date:	Tue, 07 Aug 2007 18:14:24 -0600
From:	Robert Hancock <hancockr@...w.ca>
To:	Henrique de Moraes Holschuh <hmh@....eng.br>
Cc:	Tejun Heo <htejun@...il.com>,
	Michael Sedkowski <sedmich@...il.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-kernel@...r.kernel.org,
	linux-ide@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: Disk spin down issue on shut down/suspend to disk

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@...pamshaw.ca
Home Page: http://www.roberthancock.com/

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