RAIDframe parity rebuild (was: RAIDframe performance vs. stripe size: Test Results)

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

> So a parity rebuild does so by reading all the data and the
> exiting parity, computing the new parity, and then comparing the
> existing parity with the new parity.  If they match, it's on to the
> next stripe.  If they differ, the new parity is written out.
Oops.
What's the point of not simply writing out the computed parity?

> What we don't know here is what the state of the array was when you
> started the rebuild.  That is, was the parity 'mostly correct'
> beforehand? (i.e. saving having to do a lot of the writes).
I don't know either. If the discs contained a clean RAID set with a
different SPSU, was the parity correct?