Volume is degraded (but all disks green)

Update:

mdgm and Skywalker kindly PM'd. Skywalker accessed remotely and issued a mdadm command to force the array down to 6 disks and convert back to RAID5. It looks like the issue was OS6 hadn't marked the disk as failed when it was removed before I swapped the new one in. That has now reshaped BUT.... it looks like btrfs hasn't resized correctly and I'm left 2TB short.

I've done a

btrfs fi resize max /data

as suggested by mdgm. I've also balanced the metadata and tried the resize again. Thrown in a few reboots as well!

Various outputs below.

Any advice gratefully received

Thanks

Andy

root@Pro6:~# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md126 : active raid5 sde4[0] sdb4[3] sda4[2] sdf4[1]
      5860124736 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/4] [UUUU]

md127 : active raid5 sdd3[0] sde3[4] sdf3[5] sda3[6] sdb3[7] sdc3[1]
      19510833920 blocks super 1.2 level 5, 64k chunk, algorithm 2 [6/6] [UUUUUU]

md1 : active raid6 sda2[0] sdb2[5] sdf2[4] sde2[3] sdd2[2] sdc2[1]
      2093056 blocks super 1.2 level 6, 512k chunk, algorithm 2 [6/6] [UUUUUU]

md0 : active raid1 sdd1[0] sde1[4] sdf1[5] sda1[6] sdb1[7] sdc1[1]
      4190208 blocks super 1.2 [6/6] [UUUUUU]

unused devices: <none>
root@Pro6:~# mdadm --detail /dev/md127
/dev/md127:
        Version : 1.2
  Creation Time : Thu Feb 13 19:50:29 2014
     Raid Level : raid5
     Array Size : 19510833920 (18606.98 GiB 19979.09 GB)
  Used Dev Size : 3902166784 (3721.40 GiB 3995.82 GB)
   Raid Devices : 6
  Total Devices : 6
    Persistence : Superblock is persistent

    Update Time : Sat Jan 28 10:53:58 2017
          State : clean
 Active Devices : 6
Working Devices : 6
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

           Name : 33ea2557:data-0  (local to host 33ea2557)
           UUID : 92b2bc5f:cf375e4b:5dcb468f:89d2bd81
         Events : 13329989

    Number   Major   Minor   RaidDevice State
       0       8       51        0      active sync   /dev/sdd3
       1       8       35        1      active sync   /dev/sdc3
       7       8       19        2      active sync   /dev/sdb3
       6       8        3        3      active sync   /dev/sda3
       5       8       83        4      active sync   /dev/sdf3
       4       8       67        5      active sync   /dev/sde3
root@Pro6:~# mdadm --detail /dev/md126
/dev/md126:
        Version : 1.2
  Creation Time : Tue Nov 24 12:23:49 2015
     Raid Level : raid5
     Array Size : 5860124736 (5588.65 GiB 6000.77 GB)
  Used Dev Size : 1953374912 (1862.88 GiB 2000.26 GB)
   Raid Devices : 4
  Total Devices : 4
    Persistence : Superblock is persistent

    Update Time : Sat Jan 28 10:53:57 2017
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

           Name : 33ea2557:data-1  (local to host 33ea2557)
           UUID : 4010d079:27f07b46:33b86d75:a3989442
         Events : 6475

    Number   Major   Minor   RaidDevice State
       0       8       68        0      active sync   /dev/sde4
       1       8       84        1      active sync   /dev/sdf4
       2       8        4        2      active sync   /dev/sda4
       3       8       20        3      active sync   /dev/sdb4
root@Pro6:~# btrfs fi show
Label: '33ea2557:data'  uuid: 71e6eb17-3915-4aa1-bf47-ee05fec2bcd2
        Total devices 2 FS bytes used 18.09TiB
        devid    1 size 18.17TiB used 17.16TiB path /dev/md127
        devid    2 size 3.64TiB used 1.33TiB path /dev/md126

root@Pro6:~# btrfs fi df /data
Data, single: total=18.47TiB, used=18.08TiB
System, RAID1: total=32.00MiB, used=2.03MiB
Metadata, RAID1: total=13.00GiB, used=11.57GiB
GlobalReserve, single: total=512.00MiB, used=0.00B
root@Pro6:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
udev             10M  4.0K   10M   1% /dev
/dev/md0        4.0G  721M  3.0G  20% /
tmpfs           998M     0  998M   0% /dev/shm
tmpfs           998M  6.0M  992M   1% /run
tmpfs           499M 1004K  498M   1% /run/lock
tmpfs           998M     0  998M   0% /sys/fs/cgroup
/dev/md127       22T   19T  3.8T  84% /data
/dev/md127       22T   19T  3.8T  84% /home
/dev/md127       22T   19T  3.8T  84% /apps