Arch Linux

My root filesystem is a btrfs subvolume using raid 0.

# btrfs fi show
Label: 'base2' uuid: 654e2356-3c7b-46f5-af12-60f410bce725
Total devices 2 FS bytes used 1.70TB
devid 1 size 1.84TB used 1.65TB path /dev/sdc3
devid 2 size 897.14GB used 701.17GB path /dev/sdb3

# btrfs subvolume list /
ID 261 top level 5 path @root
ID 263 top level 5 path @data
ID 3863 top level 5 path __active
ID 3864 top level 5 path __active/var
ID 3865 top level 5 path __active/usr

where _active is the actual root, @root is my old gentoo installation.

fstab line:

/dev/sdb3 / btrfs noatime,space_cache,subvol=__active,compress=lzo 0 0

grub-mkconfig somehow uses *both* drives as labels for the root fs:

------------------------
menuentry 'Arch GNU/Linux, with Linux core repo kernel' --class arch --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-core repo kernel-tr
ue-/dev/sdc3
/dev/sdb3' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_msdos
insmod ext2
set root='hd1,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd1,msdos1 --hint-efi=hd1,msdos1 --hint-baremetal=ahci1,msdos1 911f4474-389a-4d5c-8724-a9873a58dd1e
else
search --no-floppy --fs-uuid --set=root 911f4474-389a-4d5c-8724-a9873a58dd1e
fi
echo 'Loading Linux core repo kernel ...'
linux /vmlinuz-linux root=/dev/sdc3
/dev/sdb3 ro rootflags=subvol=__active radeon.modeset=1 video=DVI-0:e video=DVI-1:d
echo 'Loading initial ramdisk ...'
initrd /initramfs-linux.img
}
-------------------

notice the newlines between /dev/sdc3 and /dev/sdb3

if i remove "/dev/sdc3\n" in the entry title and the linux command everything boots fine.