Re: IBM HDAPS things are looking up (was: Re: [Hdaps-devel] Re: [ltp] IBM HDAPS Someone interested? (Accelerometer))

Pavel Machek
2005-07-04T20:23:04Z

Hi!

> > > > This is exactly what I said. Use hdparm to make the HD park
> > > > inmediatelly. I did send the email to the HDPARM developer, but he never
> > > > replied. I asked him what would be the best way to make the HD park with
> > > > no exception and then let it come back 5 or 10 seconds later.
> > >
> > > IIRC, you don't have to do anything to wake up the drive after a
> > > STANDBYNOW command, if you want to be on the safe side you just issue an
> > > IDLEIMMEDIATE. So your code will look something like:
> >
> > the problem for this will be that this app will also want to prevent ANY
> > io going to the disk for a few seconds.
> >
> > I mean, what use is parking the head if you notice the laptop falling,
> > when the kernel submits IO to it and wakes it up again before it hits
> > the ground :)
>
> Yeah, that likely needs a little help from the ide driver. If you force
> a spindown, you will effectively have parked the head for as long as the
> spindown + spinup takes. That could turn out to be enough, it will take
> more than 1-2 seconds anyways.

Actually, "spin disk down and keep it down" would be nice for other
reasons. Taking computer for a jog playing mp3s from ramdisk is
something I'd like to do...
Pavel
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