Stephane - In my case the level was Natty and the target was a Dell system with firmware RAID 1 against two 750 GB drives. It never wrote grub out. I could not get install to install grub. I ended up having to disable firmware RAID and fumbling through software RAID. Ubuntu has supported firmware RAID for several years now. I am guessing that support was regressed out.
Stephane - In my case the level was Natty and the target was a Dell system with firmware RAID 1 against two 750 GB drives. It never wrote grub out. I could not get install to install grub. I ended up having to disable firmware RAID and fumbling through software RAID. Ubuntu has supported firmware RAID for several years now. I am guessing that support was regressed out.