How to remove RAID 1 (soft)?

Question

I have been told that my dedicated server (which I use for hosting my websites) has RAID 1 (software), which makes my two disks of 750gb each, act as one, which is good for both speed and instant backup (in case one of them explodes or something)

But I'm not serving any critical application, and I would prefer to be able to use the second disk for daily or semanal backups.

So how do I remove the RAID 1 thing so I can use all the disk space as I wish?

Here's the result for $ df -h, in case you need it:

Filesystem            Size  Used Avail Use% Mounted on
/dev/md1              9.7G  1.7G  7.6G  18% /
/dev/md2              683G  290M  649G   1% /home
tmpfs                 4.0K     0  4.0K   0% /dev/shm

I'm on Centos 5.5

Solution

What you want to do is something like this:

#Break the array, removing the mirror
mdadm --manage /dev/md2 --fail /dev/sdb1
mdadm --manage /dev/md2 --remove /dev/sdb1
#Create a new file system on the mirror
mke2fs -t ext4 -j /dev/sdb1
#Mount the mirror so you can use it
mkdir /mnt/backup
mount /dev/sdb1 /mnt/backup

Please note that this is a very dangerous set of instructions, and they can destroy all your data. Do not just copy them verbatim! Make sure you have an up-to-date backup of the system and that you verify that each step is suitable for your environment.