On Fri, May 12, 2006 at 05:00:49AM +1200, Russell McMahon wrote:
> I'd be interested in taking the signals meant to write data to a CF 
> card and using them to write to two cards in parallel so that I have a 
> redundant copy. Making one card faster than the other or delaying the 
> clocking slightly would be acceptable. Without having looked into it 
> I'd imagine that two structurally identical cards should allow one 
> card to be driven "blind" without too much risk of data loss.
> 
> Comments ?
> 
> The object is to provide data backup for a system which presently 
> writes to a single CF card. Occasionally cards fail and if you want to 
> avoid this a duplicate copy is essential. The writing system is not 
> amenable to modification - the dual media system must be transparent.

Sounds like you need two controllers for sure. If you try to write them
in parallel without the full two controller setup, how will you know
when one fails?

I'd make something that can masqurade as a CF card first. Once that's
done, tested, works essentially make a RAID backend for it. Otherwise I
think it'll be hard to put in the robust error checking you sound like
you need.

-- 
pete@petertodd.ca http://www.petertodd.ca
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