Mirror of an existing filesystem with 'md'

["Mimmus" <dviggiani tiscali it>]

Hi,
I have an already existing filesystem (on /dev/sde1) and I'd like to mirror 
it on a new fs (on /dev/sdh1) using 'md', saving its content.
I think that command:
mdadm --create /dev/md0 --level=1 --raid-device=2 /dev/sde1 /dev/sdh1
makes the work but I need confirmation that filesystem on /dev/sde1 will be 
not lost.

Thanks in advance
Domenico Viggiani