Treemap, sunburst, or flame: how to read a disk map

DiskDude shows a single scan nine different ways. That is not because nine is a nice number. Each view answers one question better than the others, and knowing which one to open saves time. This post covers the three visual maps.

Treemap: what is big?

A treemap fills a rectangle with smaller rectangles. Each one is a file or folder, and its area is proportional to its size. Folders nest inside their parents.

Read it like this. The largest block on the screen is the largest thing on your drive. Click it to zoom in and see what is inside. Two or three clicks usually get you from "my drive is full" to a specific folder you can act on.

The treemap is the best first view because it needs no reading. Size is the only thing it shows, and size is usually the only thing you care about.

Sunburst: where does it sit?

A sunburst draws the same hierarchy as rings. The center is the folder you scanned. Each ring outward is one level deeper. A wide wedge is a large folder, and the wedges stacked outside it are its contents.

The sunburst is good at showing depth. A treemap can hide a large file ten folders down. In a sunburst, that file is a wide wedge on the outer ring, and you can trace it back to the center to see the full path.

Use it when the treemap shows a big block but you want to understand how it is structured before you delete anything.

Flame: how deep does it go?

A flame chart stacks folders as horizontal bars. The bottom bar is the root, and each row above it is one level deeper. Width is size, just like the other two views.

Flame charts come from performance profiling, and they are useful for the same reason here. Tall, narrow towers are deeply nested paths that take little space. Short, wide bars are the shallow folders that hold most of your data. Developer folders full of node_modules produce very tall towers, which is a quick way to spot them.

Which one should you open first?

• Treemap when you want the biggest thing, fast.
• Sunburst when you want to understand the shape of a large folder.
• Flame when you suspect deep nesting is hiding the size.

All three use the same scan, so switching between them is instant. Whichever view you are in, right-click any item to open it in Finder, look at it in Quick Look, or add it to Cleanup.

The other six views, Folders, Bubbles, Mind map, Top sizes, Age map, and List, cover the non-visual questions: what is oldest, what is largest by name, and what the raw outline looks like. We will cover those in a later post.