Hmm, I think the information in /var/log/messages are actually interesting for MD debugging.
Seems there was a bad sector somewhere in the middle of all this, which might have triggered something? Attached (gzipped - sorry for the inconvenience, but it's 5 kB vs. 250 kB!) I've cut out a lot of irrelevant cruft (kernel messages) and added comments about what I did when.
linux-22apr-messages.gz
Description: GNU Zip compressed data
