[geeks] Impressive...

[Joshua Boyd]

On Mon, Mar 09, 2009 at 12:57:05PM -0500, Jonathan C. Patschke wrote:
> On Fri, 6 Mar 2009, velociraptor wrote:
>
>> I need to educate myself more, obviously.  I didn't realize you could
>> not grow the pools transparently.
>
> You can, so long as you're not using anything other that mirroring or
> striping.  The math to make a parity-based or Reed-Solomon based
> redundancy system grow transparently is somewhere between complicated and
> impossible.

So, how do you think that Drobo is pulling off that trick?  They appear
(if their file system space estimator is to be trusted) to go from a
mirror to a raid5 transparently, and claim to be able to grow or shrink
the raid5 seemlessly.

I've been trying to figure out how they do it.