Subject: Re: how to spin down a harddisk?
To: Ken Hornstein <kenh@cmf.nrl.navy.mil>
From: Manuel Bouyer <bouyer@antioche.lip6.fr>
List: port-i386
Date: 08/02/2000 20:49:25
On Wed, Aug 02, 2000 at 01:07:29PM -0400, Ken Hornstein wrote:
> >> Then maybe the disk driver should keep track of how long the disk has been
> >> idle and always send the start/stop unit command if it's been idle more
> >> than a specific amount of time.
> >
> >The driver can't really know how long the disk has been idle because the
> >power management is done *inside the disk*.
> >And there's no start/stop command for IDE disks.
> 
> Well, that's not exactly correct.  There are IDLE and STANDBY commands
> that put the drive in the designated mode.  You don't "start" from that;
> the next command wakes up the drive.  There's also SLEEP, which requires
> a reset to spin up the drive (see atactl(8) for examples).

I can't see how this is not correct: I can't send a "start" command to the
disk before sending a read/write when in idle or standby mode.
sleep is another problem, but I don't think it's used that much (since
there's no timer for this mode).

--
Manuel Bouyer <bouyer@antioche.eu.org>
--