To me this seems like a very common situation these days, so I'm not sure why I can't find a very straightforward answer on how to proceed. I also don't know why the Ubuntu installer can't navigate this situation automagically. I'm installing a RAID1 with two 3TB drives, almost all of the volume is in the first partition, /, and about 35 GB is swap. I tried to use cfdisk to partition the disks, but that did not work because they are larger than 2TB. So I used parted, then gparted to make the partitions "raid" type, then mdadm, and it all looked good. I did all that from the Ubuntu 12.04 live CD (but had to install mdadm). I had to do that because the 2TB limit for fdisk is because of DOS label, and to get beyond that I had to use the GPT label. Next I went to the Ubuntu 12.04 Alternate CD (both CDs were AMD 64) and did the installation into the / partition, using ext4. That went great up until near the last step when it tried to install GRUB in the Master Boot Record (MBR). That step failed, returning this message: Unable to install GRUB in /dev/sda Executing 'grub-install /dev/sda' failed This is a fatal error. Everything was being installed to /dev/md0 (/) and /dev/md1 was swap. Apparently, GPT is an alternative to MBR, so that could have something to do with grub-install failing to install GRUB to the MBR. (Ya think?). So I'm not even sure of why I tried, but I didn't know what else to do at 5 am yesterday morning after fighting with this thing all last night! Now I'm back at it. I decided to continue the Ubuntu installation after the failed step. I see this message: "No boot loader has been installed, either because you chose not to or because your specific architecture doesn't support a boot loader yet. "You will need to boot manually with the /vmlinuz kernel on partition /dev/md0 and root=/dev/md0 passed as a kernel argument." That to me is completely incomprehensible. Do they mean that I should boot from a USB or CD? Then do what, exactly? Google gives so much that's just all over the map that I don't know what to do with it. If I run the Live CD, I can't see the /dev/md0 or /dev/md1 RAID1 partitions and if I run the Alternate CD, which handles RAID, it doesn't have the Live CD feature. I hope one of you will have an idea. Thanks. Mike