Subject: Re: 1.4.1, APM, SCSI disk spin down how?
To: Ken Hornstein <email@example.com>
From: Ignatios Souvatzis <firstname.lastname@example.org>
Date: 07/26/2000 09:12:25
On Tue, Jul 25, 2000 at 10:37:32PM -0400, Ken Hornstein wrote:
> I did some of the admittedly minor work with power management on IDE
> drives, so let me explain what you're up against.
> The way that power management is done on IDE drives is simple; you
> send a command to the drives to tell it to spin down after N seconds
> of inactivity. The drive wakes up when the operating system accesses
> the drive. It's completely transparent to the operating system.
One would hope that drives implementing this can withstand the stress
of repeatedly powering up/down over their lifetime...
> So, what does this have to do with SCSI drives? Well, AFAIK, SCSI
> drives don't have the feature of IDE drives that enables you to
> do the power management on the drive; you need to do it. But this
> presents a problem; you need to make the SCSI device driver aware of
> what you're doing, otherwise the operating system won't know that
> it has to turn on the drive when it goes to access it.
> work done on the i386 APM probably won't help you
Fine until here. Just make the driver aware that it has spun down the drive
and make it spin up before the next access. The reason I never did something
like this is: as the drive itself has no provision to repeatedly spin down
and up again automatically, I'd expect that doing so will affect its