RAIDframe: what if a disc fails during copyback

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

(I could probably direct this question to oster@ instead of tech-kern@)

In a RAIDframe RAID-1, a disc failed and I reconstructed on a spare.
Now I want to replace the failed component (actually by the same disc, 
which needed a firmware update) and want to copyback to it.
How will RAIDframe behave if, during the copyback:
1. The replaced component fails
2. The spare fails
3. The other, non-replaced component fails?

Specifically: Is there any szenario (other than more than one disc failing) 
that will put the RAID into a non-redundant state? I guess 3. may?