maff@druadan ~ $ sudo btrfs filesystem usage /srv
WARNING: RAID56 detected, not implemented
WARNING: RAID56 detected, not implemented
WARNING: RAID56 detected, not implemented
Overall:
    Device size:                   7.28TiB
    Device allocated:            156.00GiB
    Device unallocated:            7.12TiB
    Device missing:                  0.00B
    Used:                        154.56GiB
    Free (estimated):             49.56TiB      (min: 3.57TiB)
    Data ratio:                       0.14
    Metadata ratio:                   0.06
    Global reserve:              512.00MiB      (used: 144.00KiB)

Data,RAID1: Size:77.00GiB, Used:76.43GiB
   /dev/sdb       25.00GiB
   /dev/sdc       26.00GiB
   /dev/sdd       26.00GiB
   /dev/sde       77.00GiB

Data,RAID5: Size:994.00GiB, Used:993.11GiB
   /dev/sdb      497.00GiB
   /dev/sdc      497.00GiB
   /dev/sdd      497.00GiB

Metadata,RAID1: Size:1.00GiB, Used:864.19MiB
   /dev/sdb        1.00GiB
   /dev/sde        1.00GiB

Metadata,RAID5: Size:35.00GiB, Used:17.65GiB
   /dev/sdb       17.50GiB
   /dev/sdc       17.50GiB
   /dev/sdd       17.50GiB

System,RAID5: Size:64.00MiB, Used:144.00KiB
   /dev/sdb       32.00MiB
   /dev/sdc       32.00MiB
   /dev/sdd       32.00MiB

Unallocated:
   /dev/sdb        1.29TiB
   /dev/sdc        1.29TiB
   /dev/sdd        1.29TiB
   /dev/sde        1.74TiB