device delete: more informations

Hallo,

I've made a 2-partitions system with

        mkfs.btrfs -P Probe -m raid1 -d raid0 /dev/sdb1

        mount LABEL=Probe /mnt/Probe

        btrfs device add /dev/sdb2 /mnt/Probe

"btrfs-show" (and other tests) showed that all worked well.

        btrfs device delete /dev/sdb2 /mnt/Probe

only showed "error" (I haven't noticed the long text, something like  
"can't delete"); but "dmesg" showed the reason:

  btrfs: unable to go below two devices on raid1

Could this message also shown in the "regular" error message?

Viele Gruesse!
Helmut