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Date:      Mon, 22 Aug 2005 19:20:51 +0200
From:      Gary Jennejohn <garyj@jennejohn.org>
To:        freebsd-hackers@freebsd.org
Subject:   Re: IBM Active Protection System Approach 
Message-ID:  <200508221720.j7MHKpNb022773@peedub.jennejohn.org>
In-Reply-To: Your message of "Mon, 22 Aug 2005 17:55:42 %2B0200." <5FFDC44D-F094-4856-8FAC-4D14EB77B47A@sarenet.es> 

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Borja Marcos writes:
> > Søren Schmidt writes:
> > I think this will need to be tailored to the exact type of "mishap"  
> > one wants to protect against.
> 
>      I think that the main purpose of the shock detection system is  
> to allow data to be recovered from the disk in case the laptop is  
> broken. By parking the heads asap you can avoid damaging the plates  
> with the head.
> 
>      At least that's what I read. The disk won't be necessary usable  
> after being dropped, but at least the plates should be readable.
> 
>      In that case, priority number one would be a fast parking of the  
> head. However, it could lead to a worst-case data loss with  
> softupdates and the disk cache, isn't it?
> 

It seems to me that the worst-case scenario, dropping the laptop,
would result in extremely high G-loading in microsecomds rather than
milliseconds. Not much can be done to save the disk in such a short
time.

A scenario where the user bumps the laptop while in use might be
helped, though.

---
Gary Jennejohn / garyjATjennejohnDOTorg gjATfreebsdDOTorg garyjATdenxDOTde




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