raid0 needs mounting alternate device every boot? open_ctree failed (3.19.5)

[Marc MERLIN <marc@merlins.org>]

This is the weirdest thing:
gargamel:/var/log# mount /dev/mapper/raid0d2 /mnt/btrfs_space
mount: wrong fs type, bad option, bad superblock on /dev/mapper/raid0d2,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so
[  835.718898] BTRFS info (device dm-5): disk space caching is enabled
[  835.778580] BTRFS: failed to read the system array on dm-5
[  835.819223] BTRFS: open_ctree failed

gargamel:/var/log# mount /dev/mapper/raid0d1 /mnt/btrfs_space
[  847.047607] BTRFS: device label btrfs_space devid 1 transid 40929 /dev/mapper/raid0d1
[  847.073955] BTRFS info (device dm-4): disk space caching is enabled

The previous boot, I had to mount raid0d2 because raid0d1 didn't work.

Label: 'btrfs_space'  uuid: 01334b81-c0db-4e80-92e4-cac4da867651
        Total devices 2 FS bytes used 401.54GiB
        devid    1 size 836.13GiB used 295.02GiB path /dev/mapper/raid0d1
        devid    2 size 836.13GiB used 295.01GiB path /dev/mapper/raid0d2

Data, RAID0: total=580.00GiB, used=398.22GiB
System, RAID1: total=8.00MiB, used=64.00KiB
System, single: total=4.00MiB, used=0.00B
Metadata, RAID1: total=5.00GiB, used=3.08GiB
Metadata, single: total=8.00MiB, used=0.00B
GlobalReserve, single: total=512.00MiB, used=0.00B

Those are 2 crypted disks which are already decrypted by the time I try
to mount them, I just don't understand why btrfs fails if I mount
one device but works with the other one, or the other way around.

Any idea what could be causing this?

Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/                         | PGP 1024R/763BE901