Everything on the system seems to work just fine up to the grub installation. Running grub --no-floppy and asking for the partitions of hd0 (hitting tab) results in: Possible partitions are: Partition num: 0, Filesystem type unknown, partition type 0xfd Partition num: 1, Filesystem type unknown, partition type 0xfd Partition num: 2, Filesystem type unknown, partition type 0xfd Partition num: 4, Filesystem type unknown, partition type 0xfd Partition num: 5, Filesystem type unknown, partition type 0xfd I'm not sure whether it should be saying ext2fs or ext4fs, but clearly it shouldn't say unknown. If I try root (hd0,0) and setup (hd0) root complains about Filesystem type unknown and setup gives Error 17: Cannot mount selected partition. I assume these two errors are to be expected given that it can't figure out the filesystem type. In case it matters, I created the partitions with "mkfs.ext4 /dev/md1 -L="/"" and similarly for the 2,3,5,6 partitions. Also, as you can see, I set the partition type to 0xfd (linux raid autodetect). Reproducible: Always Steps to Reproduce: 1. Boot with livedvd 2. Mount up: mount /dev/md1 /mnt/gentoo ... mount -t proc none /mnt/gentoo/proc mount --rbind /dev /mnt/gentoo/dev 3. chroot sudo chroot /mnt/gentoo /bin/bash env-update source /etc/profile export PS1="(chroot) $PS1" 4. grub grub --no-floppy root (hd0,0) setup (hd0) Actual Results: grub> root (hd0,0) Filesystem type unknown, partition type 0xfd grub> setup (hd0) Error 17: Cannot mount selected partition grub> Expected Results: grub> root (hd0,0) grub> setup (hd0) grub> This is a fresh install following the Gentoo Linux AMD64 Handbook. I got up to the 10.b. step and nothing caused any problems until this. The documentation I used for setting up the raid is http://en.gentoo-wiki.com/wiki/RAID/Software (used google cache because gentoo-wiki seemed to be down).
Which partition is that? If it's /boot, then why don't you mount it manually before grub attempts to?
Resolved: was not using version 0.9 metadata. The documentation suggests that only the kernel will have trouble detecting the raid (which could probably be handled by specifying a md= command to the kernel). In reality, both the kernel and grub have issues with mdraid other than 0.9.
