lkml.org 
[lkml]   [2007]   [Aug]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Disk spin down issue on shut down/suspend to disk
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/

\
 
 \ /
  Last update: 2007-08-08 06:31    [W:0.043 / U:0.356 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site