Is there any way to create a software raid 1 on the / partition without losing data?

I've installed Ubuntu on a hard drive. I added a 2nd hard drive and now want to create a software raid 1 mirror for the / partition. How do I do this? If I used the mdadm command, it says that the device is busy or in use.

I have tried using the rescue boots and creating the raid using fdisk and mdadm and editing grub to reflect the new /dev/md0, but when I boot I get some kernel panicks.

Is there any way to create a software raid 1 on the / partition?

Warren Togami, of RedHat, has come up with a scheme that is alleged to work, at least on RedHat distributions. I think it will generalize, and the web page is good reading anyway, to let you know what is involved in booting from a RAID volume. Your kernel panics are almost certainly a side effect of not having the RAID stuff started by the time that the kernel first starts up; I saw the same thing when I was confused about the difference between Software RAID and FakeRAID. Here is the link to Warren's page: http://togami.com/~warren/guides/remoteraidcrazies/

Thanks for the link! I appreciate it. Looks like it's going to be pretty tricky to get it going, but I will let you know if it works on an Ubuntu machine. I will first test it in VMware