I have a fake raid, which I wanted to access using

mdadm /dev/md0 -A -c 128 -l stripe --verbose /dev/sda /dev/sdc

which should be right, as far as I understand the man page. But I get the message

mdadm: option -l not valid in assemble mode

leaving the offending option out leads to

mdadm: failed to create /dev/md0

and (despite verbose) no more information. I'm assuming that -A requires some mdadm-specific header which is obviously missing. I probably need to use "build" instead of assemble, but from the description I'm really unsure whether this is a non-destructive operation. Is it? What should I exactly do?

UPDATE

I see I haven't made clear, that the array already exists as a fake-raid (I can't give the details about my mainboard now). It looks like doing nothing except for interleaving blocks, so I hoped it could be easily done using mdadm, too. Maybe I'm completely wrong, but all the info I've found was concerned with booting from fake-raid, what I don't really need. I'd be happy with a read access for now.