The new Apple File System (APFS) was one of the most important and exciting changes introduced in macOS High Sierra. However, with all its new power, APFS also brought a number of new questions to Mac users, which we see asked in numerous online forums and in support tickets that we receive.
Disappearing disk space
Free disk space sometimes mysteriously disappears — the sum of all existing files does not match the free space. Why?
Deleting files doesn’t help
Despite you delete tens of GBs of unneeded files, the disk’s free space doesn’t grow at all. Why?
System taking too much space
About This Mac > Storage shows the yellow “System” segment unrealistically large — tens of GBs, or up to 80% of your disk. Why?
DaisyDisk scans your entire disk and builds a size-oriented map of your files and folders. It can reach even restricted and system folders by scanning with raised access permission.
The remaining used space, if any, DaisyDisk displays as well, labeling it as “hidden space”.
The new DaisyDisk can additionally single out the “purgeable space” inside the “hidden space”. You can forcedly delete it by a simple drag-and-drop to the Collector at the bottom, like you would do with a regular file.