ERROR: error removing the device '/dev/sdXN' - Inappropriate ioctl for device

[Martin <m_btrfs@ml1.co.uk>]

Help welcomed...


Trying to delete one device from a btrfs raid1 across 3 devices gives
for my example:


btrfs device delete /dev/sdf5 /mnt/data2

ERROR: error removing the device '/dev/sdf5' - Inappropriate ioctl for
device


That part of the filesystem is:

Label: 'btrfs_data2'  uuid: 3aaee716-b98b-4c86-ba5a-53456994f152
        Total devices 3 FS bytes used 192.45GiB
        devid    1 size 206.47GiB used 206.02GiB path /dev/sdb5
        devid    2 size 206.47GiB used 206.47GiB path /dev/sdd5
        devid    3 size 206.47GiB used 206.47GiB path /dev/sdf5


All on: 3.14.10-gentoo


Before I do a mega-yank-up to the 3.18 kernel, is the above a known
problem or am I missing something?


(Device delete needed due to that device throwing sector errors :-( )

Thanks,
Martin