The metadata of a BTRFS file system is organized in the form of multiple B-trees, which consist of nodes. Each node is 16 KiB in size.
This page shows the contents of a single metadata chunk. Every little box is one node of 16 KiB. Together they add up to the total size of the chunk. We show 64 nodes per row, so each row is 1 MiB.
The colors indicate which B-tree the node belongs to. Most of them belong to the filesystem trees. There is one filesystem tree for every subvolume, but we draw them all in the same color here. The other trees are:
| root tree | ||
| extent tree | ||
| chunk tree | ||
| device tree | ||
| checksum tree | ||
| uuid tree | ||
| free space tree | ||
| other trees | ||
| filesystem trees |