mdadm container! How does it work

Hi everyone,

I am not sure if I understand how mdadm --create /dev/md0 --level=container works?
A device called /dev/md0 appears in /proc/mdstat but I am not sure how to use that device?

I have 2 blank drives with 1 500GB partition on each. I would like to setup mirroring, but not in the way that you have to create partition of the size that you want mirror to be. I am not sure if container does that or not? I have looked all over the net and was unable to find any info.

If someone can give me more info on it, it would be greatly appreciated!