[root@rasmusahome ralle]# btrfs fi show
Label: 'Fortune'  uuid: f87c173c-c873-424f-9c79-3be2c4d37d88
	Total devices 4 FS bytes used 1.09TiB
	devid    3 size 465.76GiB used 330.00GiB path /dev/sdc1
	devid    4 size 931.51GiB used 796.03GiB path /dev/sda1
	devid    5 size 1.46TiB used 788.03GiB path /dev/sdb1
	devid    6 size 3.64TiB used 338.00GiB path /dev/sdd1

Label: 'Glassbox'  uuid: ca44c8e4-1a26-4b4a-ba52-38a4b0d3f104
	Total devices 1 FS bytes used 273.96GiB
	devid    1 size 2.17TiB used 394.04GiB path /dev/sdb2

[root@rasmusahome ralle]# btrfs fi df /mnt/fortune/
Data, RAID1: total=1.09TiB, used=1.08TiB
System, RAID1: total=32.00MiB, used=192.00KiB
Metadata, RAID1: total=11.00GiB, used=8.78GiB
GlobalReserve, single: total=512.00MiB, used=0.00B

[root@rasmusahome ralle]# mount
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
sys on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
dev on /dev type devtmpfs (rw,nosuid,relatime,size=3931268k,nr_inodes=982817,mode=755)
run on /run type tmpfs (rw,nosuid,nodev,relatime,mode=755)
/dev/sdc1 on / type btrfs (ro,relatime,space_cache,subvolid=1187,subvol=/linux)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/net_cls type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=27,pgrp=1,timeout=0,minproto=5,maxproto=5,direct)
configfs on /sys/kernel/config type configfs (rw,relatime)
tmpfs on /tmp type tmpfs (rw)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime)
mqueue on /dev/mqueue type mqueue (rw,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,relatime)
/dev/sdc1 on /mnt/fortune type btrfs (ro,relatime,space_cache,subvolid=5,subvol=/)
/dev/sdc1 on /home type btrfs (ro,relatime,space_cache,subvolid=5,subvol=/home)
/dev/sdb2 on /mnt/glassbox type btrfs (rw,relatime,space_cache,subvolid=5,subvol=/)
tmpfs on /run/user/1000 type tmpfs (rw,nosuid,nodev,relatime,size=786796k,mode=700,uid=1000,gid=100)
fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime)
gvfsd-fuse on /run/user/1000/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=1000,group_id=100)