IBM Active Protection System Approach

[Søren Schmidt]

On 22/08/2005, at 10:08, m.ehinger at ltur.de wrote:

> what would be the best approach to implement aps on FreeBSD?
>
> I got an Accelerometer driver which will deliver data. First  
> Version is available at
> https://sourceforge.net/project/showfiles.php? 
> group_id=138242&package_id=160977
>
> We have to poll the device for information quiet often to detect a  
> possible shock early enough to park disk drive heads.

Urhm, what type of "accidents" is it we want to protect against here ?

It will take several tens of mS to get the heads parked if not  
hundreds, and the worst case scenario would be that the "accident"  
will happen just as the heads are on the way to the parking zone  
which would *really* destroy data on there, unless the disk has  
special HW to just quickly lift the heads or something.

> What else must be done to prevent a possible data loss?

I think this will need to be tailored to the exact type of "mishap"  
one wants to protect against.

If this is a way to protect against dropping a notebook on the floor  
then there won't be time for much else than trying to rush the heads  
to the parking zone.
In other setups a flush of buffers (OS level as well as HW level)  
could be preferred if power loss or HW failure was imminent.


- Søren