I currently switched my BTRFS-based gentoo system to using raid1 (basically a 2nd harddisk got unused, so I used it as raid1).
I could extend the btrfs filesystem with a second device in raid1 mode. But since then grub2 will not boot any longer. Is it possible to let grub2 boot into a btrfs root filesystem which uses raid1 (and is on a subvolume), without having an initramfs? Until yet I never used an initramfs, because on gentoo this seems to be a bit too complex.
When I try booting, I only get kernel panics - it seems the kernel cannot properly mount the rootfs. Until I switched to raid1 for the rootfs, though, the system did boot normally, so this seems to be caused by raid1.
Another related question - both partitions (sda5,sdb5) used for the rootfs have the same UUID. Is this normal?