It is recommended that Btrfs filesystems should be optimized periodically with a command like this:
btrfs balance start -dusage=5 / . The last argument is the mount point of the filesystem.
I have created a Btrfs storage on an empty block device (disk). It seems that the disk and the filesystem are completely managed by LXD, and I don’t see how I can run the balancing command on it (there is no mount point). Or maybe LXD takes care of it automatically, and I don’t need to worry about this?