btrfs cannot show you how much disk space is being referred to by each subvolume, as its used and free space tracking is only per pool. The only way to see how

btrfs cannot show you how much disk space is being referred to by each subvolume, as its used and free space tracking is only per pool. The only way to see how much space a particular subvolume is taking is to use du, which gets slower the bigger the subvolume gets. This is no longer true. As of Linux 3.6, btrfs has the ability to apply quotas to subvolumes.