Hello,

> This PC104+ computer is carried on a moving platform and occationallyy
> subject to high vibration. I do have know when vibrarion will start and
> the duration of the vibration.

Using a spinning hard disk, this is bad, even if put to sleep.

> Some time I do attach an IDE hard disk (40-160GB) to my embedded Linux
> system for high speed high volume data logging. Due to the occational
> vibration, I would like to be able to park the hard disk heads just
> before the vibration starts and re-activate logging when vibration
> ends.

I don't believe modern disks have a special "parking position" but you could
stop them spinning.

> I wonder if there is a way of temporarily moving the harddisk heads to
> parking position and back?

You can put the disk directly into standby or suspend mode using "hdparm -y"
respective "hdparm -Y". hdparm is included with busybox, with the needed
parameter, if I remember correctly.

Another idea would be to set the spindown timer very low (hdparm -S), so
that the disk spins down after maybe 5 seconds of inactivity. But you have
to ensure that no further accesses occur. Then you only have to stop
activity on the disk before vibrations occur. But it won't be good for your
disk as it shouldn't vibrate while spinning...

Hope this helps,

Sebastian

On Wed, 5 Jul 2006 21:25:40 +0200, Sebastian wrote:


>Hello,

>> This PC104+ computer is carried on a moving platform and occationallyy
>> subject to high vibration. I do have know when vibrarion will start and
>> the duration of the vibration.

>Using a spinning hard disk, this is bad, even if put to sleep.

>> Some time I do attach an IDE hard disk (40-160GB) to my embedded Linux
>> system for high speed high volume data logging. Due to the occational
>> vibration, I would like to be able to park the hard disk heads just
>> before the vibration starts and re-activate logging when vibration
>> ends.

>I don't believe modern disks have a special "parking position" but you could
>stop them spinning.

I believe they still have a parking position, but you don't have to manually
position them. They snap the heads to a safe location using internal stored
power when power is removed.