I have been using a technique that at least for me greatly simplifies moving to and from RAID-1 on any system. I do this by installing the system on a degraded RAID-1 array and then later it is very simple to make the system true RAID by just adding the missing drive/partitions. In Disk Druid I would like to see the ability to install on a degraded RAID-1 array where I declare RAID-1 but then the second mirror is missing. I install this way all the time on systems and then when I add the second hard drive later and place it into the array, it just syncs. Want to go back to just a single drive - no problem. Just fault the device and remove it. No complicated remounting filesystems or anything - very smooth. This way you're always on an md device. I would like to see this actually become the default. It makes it very easy to convert a system to RAID-1 later on if the user would like to do so without any complicated procedures necessary.
Just to clarify our setup. We establish the degraded RAID-1, let's say /dev/md0, and then we use this device as an LVM physical device and layer LVM over the RAID. Then we mount an LVM logical device (eg: /dev/mapper/VolGroup00-LogVol00) containing the root (/) filesystem. The point being that the degraded RAID-1 is no different than using any other RAID device to form a filesystem mounting solution.
*** This bug has been marked as a duplicate of 188314 ***