On Tue, 20 Aug 2013 16:08:47 +0200 Francis Moreau [off-list ref]
wrote:

hi,

It looks like a process wait uninterruptibly when it tries to access
an array which is not running yet.

Furthermore once the process is waiting, I can't start/stop the array anymore.

So I need to reboot my system and be sure next time that any processes
don't try to access a not yet running array.

Is that expected ?

No.

To be able to say more I would need lots more details.
What is the exact state of the array (cat /proc/mdstat ;mdadm -D ...)
Where is the process waiting (cat /proc/PID/stack)
What sort of "access"
How did the array get to the "not running yet" state?
Any kernel messages?
Anything else that might be relevant.

NeilBrown