Third update: I made it work. I had some space on the drive so I created new partition for / where I installed F12. Raid/LVM2 support in F12 upgrade DVD is not completely broken but it displays errors and warning when it tries to mount/inspect my raid1 md partitions (I have lvm2 on top of them). Anaconda stops and restarts md arrays several times. I have about 10 of them and whole this procedure takes about 15 minutes... Once F12 was installed the boot process was smooth and no errors or new warnings were displayed.