Re: error opening /dev/md2: No such file or directory

Robin Bowes wrote:

# mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/sdc1 missing
mdadm: error opening /dev/md2: No such file or directory

This is a side-effect of the way that the MD driver operates in a 
dynamic /dev environment. mdadm needs the /dev/mdX node to be available 
to be able to manipulate the array, but it doesn't exist until the array 
has been created. Catch-22.

At some point mdadm and the MD driver need a new communication method 
that uses a common device node for all arrays, but that won't happen soon.

In the meantime, you can manually create /dev/mdX nodes with mknod, just 
as you would have done before. Once the array is created, if you have it 
set to auto-start (using 0xfd partition types), it the device node will 
automatically appear when you boot your system. If you don't have it set 
to auto-start, you'll have to add the "mknod" command to your system 
startup scripts before trying to start the array directly.