Re: power off disk drives while running
- From: "Brennan Ashton" <comphappy@xxxxxxxxx>
- Date: Sat, 18 Aug 2007 11:21:02 -0800
On 8/18/07, Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx> wrote:
On Aug 18 2007 12:08, Marty Leisner wrote:
In embedded system design, it may be useful to poweroff the disks (as opposed
to merely spinning them down). We want to leave the system running while
the disk is powered down, and let the disk powerup when it needs to be
spun up.
That means you also have to power it on...
While the "power off mechanism" would be platform dependent, is there a
generic path to announce "prepare for power going away"?
I do not see why that would be needed from a software point of view. Just make
sure that the disk does not needlessy emergency-park when pulling power. When
someone wants to write to disk, the request goes to the device driver, which
hands it to the controller, which hands it to the disk. And your controller
should be able to handle it (e.g. wait until reconnect) when there is a request
for a disk that is powered off.
Jan
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I see this a a very important feature in the embedded system relm, I
have worked on two projects that required extreme power management,
and massive data storage. The ability to fully turn off a drive while
the system is running is key. It seems like this should be able to be
done from a kernel point of view rather than extra hardware. Although
if is not in the IDE/SATA spec then extra hardware would be necessary.
--
Brennan Ashton
Bellingham, Washington
"The box said, 'Requires Windows 98 or better'. So I installed Linux"
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