From: https://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices

    1 Multiple devices
        1.1 Current status
        1.2 Raid 5 and Raid6
        1.3 Filesystem creation
        1.4 Device scanning
        1.5 Adding new devices
            1.5.1 Conversion
        1.6 Removing devices
        1.7 Replacing failed devices
        1.8 Registration in /etc/fstab

From: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Storage_Administration_Guide/btrfs-integrated_volume_management.html

Same info as above