I have Ubuntu 11.04 running on my home desktop which has 2 hard drives mirrored by RAID.

The drives are partitioned with a big data partition, a swap partition and a couple of 20Gb partitions for OSes, one is 11.04 which is in use, and the other is kept spare for installing a later version. Which is what I'd like to do now.

The idea of a 2nd partition for new OS is that I can try it, and if it's problematic, I can boot back into the original one - the machine is shared with others, so I need it to stay available!

I have had horrible problems with software RAID after using a Live USB stick - basically it messes up the internal numbering of the RAID drives or something, anyway, the result is you can't boot after using it :-( and have to spend ages re-assembling the arrays, trying to remember grub commands etc etc. Quite a shocker when you consider booting from a Live USB is supposed not to affect the existing system.

As I'm installing in a RAIDed disc, I would typically use the Alternative install (sad to hear that this is going to be dropped in future).

However, I think I might be able to use unetbootin to trick the system into working on top of the existing system that understands RAID, with the normal ISO?

If unetbootin loads from drives that are already understood to be RAIDED, then presumably it will only see md0... instead of sda, sdb... and as long as I don't need to repartition (I don't) it should be fine, right?

Or is that just plain foolishness? Please tell me before I end up with a dead system (again!)