menuentry "Fedora release 16 (Verne) (on /dev/sda3)" {
        insmod ext2
        set root='(hd0,3)'
        search --no-floppy --fs-uuid --set 5895fab5-3c8d-48fb-b8ae-ffba30048a2a
        linux /boot/vmlinuz-3.1.9-1.fc16.x86_64 root=/dev/sda3
}

[root@localhost ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
/sbin/grub2-probe: error: cannot stat `/dev/root'.

[root@localhost ~]# grub2-install /dev/sda
/sbin/grub2-probe: error: cannot stat `/dev/root'.

if [ -s $prefix/grubenv ]; then
  load_env
fi
set default="0"
if [ ${prev_saved_entry} ]; then
  set saved_entry=${prev_saved_entry}
  save_env saved_entry
  set prev_saved_entry=
  save_env prev_saved_entry
  set boot_once=true
fi

function savedefault {
  if [ -z ${boot_once} ]; then
    saved_entry=${chosen}
    save_env saved_entry
  fi
}

function recordfail {
  set recordfail=1
  if [ -n ${have_grubenv} ]; then if [ -z ${boot_once} ]; then save_env recordfail; fi; fi
}
insmod ext2
set root='(hd0,9)'
search --no-floppy --fs-uuid --set 11e7d1aa-6345-4551-9799-fe823b818e90
if loadfont /usr/share/grub/unicode.pf2 ; then
  set gfxmode=640x480
  insmod gfxterm
  insmod vbe
  if terminal_output gfxterm ; then true ; else
    # For backward compatibility with versions of terminal.mod that don't
    # understand terminal_output
    terminal gfxterm
  fi
fi
insmod ext2
set root='(hd0,9)'
search --no-floppy --fs-uuid --set 11e7d1aa-6345-4551-9799-fe823b818e90
set locale_dir=($root)/boot/grub/locale
set lang=fr
insmod gettext
if [ ${recordfail} = 1 ]; then
  set timeout=-1
else
  set timeout=10
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Ubuntu, avec Linux 2.6.32-37-generic' --class ubuntu --class gnu-linux --class gnu --class os {
        recordfail
        insmod ext2
        set root='(hd0,9)'
        search --no-floppy --fs-uuid --set 11e7d1aa-6345-4551-9799-fe823b818e90
        linux   /boot/vmlinuz-2.6.32-37-generic root=UUID=11e7d1aa-6345-4551-9799-fe823b818e90 ro   quiet splash
        initrd  /boot/initrd.img-2.6.32-37-generic
}
menuentry 'Ubuntu, avec Linux 2.6.32-37-generic (mode de dépannage)' --class ubuntu --class gnu-linux --class gnu --class os {
        recordfail
        insmod ext2
        set root='(hd0,9)'
        search --no-floppy --fs-uuid --set 11e7d1aa-6345-4551-9799-fe823b818e90
        echo    'Chargement de Linux 2.6.32-37-generic ...'
        linux   /boot/vmlinuz-2.6.32-37-generic root=UUID=11e7d1aa-6345-4551-9799-fe823b818e90 ro single 
        echo    'Chargement du disque mémoire initial ...'
        initrd  /boot/initrd.img-2.6.32-37-generic
}


[...]

menuentry "Fedora release 16 (Verne) (on /dev/sda3)" {
        insmod ext2
        set root='(hd0,3)'
        search --no-floppy --fs-uuid --set 5895fab5-3c8d-48fb-b8ae-ffba30048a2a
        linux /boot/vmlinuz-3.1.8-2.fc16.x86_64 root=/dev/sda3
}
menuentry "Fedora release 16 (Verne) (on /dev/sda3)" {
        insmod ext2
        set root='(hd0,3)'
        search --no-floppy --fs-uuid --set 5895fab5-3c8d-48fb-b8ae-ffba30048a2a
        linux /boot/vmlinuz-3.1.9-1.fc16.x86_64 root=/dev/sda3
}

Tu crées le initramfs avec dracut

[root@localhost ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
/sbin/grub2-probe: error: cannot stat `/dev/root'.

[root@localhost ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
/sbin/grub2-probe: error: cannot stat `/dev/root'.

grub-mkdevicemap
update-grub