[CentOS] OT: Quick ext3 command

Hello,

Sorry for the off-topic, but I've just installed CentOS 5 on my home
box and I want to put the journal on another drive. I created a
software RAID-1 device, /dev/md1, and formatted an ext3 file
system on it. Now I want to move the journal to /dev/hda5. I've
googled for this and the process appears to be:

mkfs.ext3 -b 4096 -O journal_dev /dev/hda5
mkfs.ext3 -b 4096 -J device=/dev/hda5 /dev/md1

Now, here's the fun part. I've already put data on /dev/md1.
Will the above commands reformat /dev/md1? If so, is there
an easy way to move the journal for /dev/md1 to a new
partition?

TIA!

Jeff