Comment 8 for bug 1267569

Here is another workaround

I had 3 disks sda, sdb and sdc then I removed boot section via CLI

    fuel provisioning --env-id 1 --default -d

    # remove this section for sdc
    - size: 300
      type: boot
    - file_system: ext2
      mount: /boot
      name: Boot
      size: 200
      type: raid

    fuel provisioning --env-id 1 -u

    # run deployment

And there was no raid partition on sdc

    [root@node-2 ~]# cat /proc/mdstat
    Personalities : [raid1]
    md0 : active raid1 sda3[0] sdb3[1]
          204736 blocks super 1.0 [2/2] [UU]

For the next release we decided to make a special checkbox to not allocate raid on all disks.
Here is blueprint https://blueprints.launchpad.net/fuel/+spec/nailgun-bootable-checkbox-for-disks