1.4.1, APM, SCSI disk spin down how?
Anne Bennett
How do I get my SCSI drives to spin down when there's nothing going
on? The hardware manual for my motherboard implies that the BIOS
power management will deal with IDE drives only. I thought I might
add something to the "standby" script and let APM do the work, but
after reading a few "scsi" and "sd" and "ioctl" manpages, I'm still in
the dark as to how to send a command to a SCSI disk to tell it to
power down. Pointers appreciated.
(It may be that APM is not the right way to do this; my system is an
oldish Pentium desktop, and I'm not too concerned about power
consumption, but this is a small apartment, and I'd like some blessed
quiet around here when the computer's not busy, so I'm looking for
ways to stop the loudest moving parts.)
Anne.
--
Ms. Anne Bennett, Senior Analyst, IITS, Concordia University, Montreal H3G 1M8
an...@alcor.concordia.ca +1 514 848-7606
Manuel Bouyer
>
> How do I get my SCSI drives to spin down when there's nothing going
> on? The hardware manual for my motherboard implies that the BIOS
> power management will deal with IDE drives only. I thought I might
> add something to the "standby" script and let APM do the work, but
> after reading a few "scsi" and "sd" and "ioctl" manpages, I'm still in
> the dark as to how to send a command to a SCSI disk to tell it to
> power down. Pointers appreciated.
There's nothing available for this yet. Hacking the sd driver to do a simple
power management shouldn't be hard.
--
Manuel Bouyer <bou...@antioche.eu.org>
--
Ignatios Souvatzis
> 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
lifetime.
Regards,
-is
Manuel Bouyer
> Okay, fine, you probably knew all of that. Well, this is my
> way of explaining that you definately need some kernel support for
> doing this. What _I_ would do is set a flag marking that device as
> down, so the device driver knows to spin it up when it goes next
> to access it. Maybe define a new ioctl that told the SCSI subsystem
This shouldn't be needed, sd.c already knows to respin the drive up when
needed.
--
Manuel Bouyer, LIP6, Universite Paris VI. Manuel...@lip6.fr
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