Comment # 2 on bug 939748 from Neil Brown

Ouch.

It looks like the RAID signatures were still on the drives even though you had
disabled RAID in the bios.
linux/mdadm saw the signatures and assembled the array.
I guess it must have then copied all (or at least some) of the openSUSE
partitions over the windows partitions.

To erase the RAID signature you might need to boot from a rescue CD or similar,
stop any array (mdadm -Ss) and zero out the metadata (mdadm --zero --force
/dev/sd[ab]).

But that won't bring your windows data back.  It seems very likely that has
been written over.

I wonder how many people have RAID signatures on their devices but aren't using
RAID... it sounds very dangerous.  I'll have to see if there is something I can
do to make it less risky.