It’s well-known in the Mac professional community.

Many online tutorials will advise you to quit every program and delete the contents of this cache directory if you’re running out of storage space. You safely delete these files without losing any valuable data. Cache files are generally not considered to be valuable. The directory is excluded by Time Machine and other back-up programs. Cache files are files that programs can recreate by redownloading them from the internet or by performing a local operation on another set of files. This directory is where programs are supposed to store cache files. The “primary” user cache directory is stored in ~/Library/Caches/ directory in your Home folder. The rest of this article explores where to find this directory, what it’s for, and what Apple can do better to prevent this from happening. It was all taken by junk files stored in my hidden DARWIN_USER_CACHE_DIR directory. Upon closer inspection of my disk, however, I found where the missing storage space had gone.

The problem began when MacOS migrated to the Apple File System ( APFS), and everyone and their pets attributed the problem to vague APFS related issues. For over a year, I wrongly attributed the storage space to unicorn file-system features like snapshots. However, I couldn’t account for about 130 GB of storage space on my Mac. I checked every file and directory, and used various apps to assess what took up my storage space. So, where did the storage space go? and how is it all Apple’s fault? My MacBook only has 250 GB of storage, but 130 GB of storage space went missing for over a year.

How to clean macbook air storage