Bug 132706

This is solved with mdadm-1.9.0-3.  Use the --auto=md flag to create a regular
md device file if it doesn't exist or use the --auto=mdp flag to create a
partitionable md device if it doesn't exist (but you have to use a name other
than /dev/md* when using partitionable devices, for example I created a 16
partition md device on an external FC array using this command:

[root@pe-fc4 ~]# mdadm -C /dev/fcarray -l 5 -n 4 --auto=mdp16 /dev/md0 /dev/md1
/dev/md2 /dev/md3

note that I used stacked md devices, and there are some bugs in stacked md
device handling in the mdadm-1.9.0 package, specifically it doesn't do mdadm -E
properly on stacked devices, but it does start them OK).

I don't think the need for --auto=md is, well, auto enough.  If you're using one
of the standard device name, I can't think of any reason to not go ahead and
create the device if it's not there, since all the info can be inferred from the
device name.

I changed the default setting of auto= to do as you wish.  As of
mdadm-1.11.0-2.fc4 in dist-FC4-HEAD this now works the way you want.