An old install after many years can eat up a fair amount based on types of applicatios and how frequently applications are installed. A fresh install of macOS will have very little 'System Data'. Generally over time, when installing various Applications and utilities, they will also install items into the Libraries and accumulate.

/usr - This is where CLI utilities installed by Homebrew and other applications end up.~/Library - This is hidden by default (more on this in a minute), but it uses a very similar structure to /Library with a large number of files landing in ~/Library/Application Support, things like Apple Messages, Apple Photo Libraries, Xcode Simulators, Crossover Bottles (games), Docker Containers, and Steam games within ~/Library/Application Support or ~/Library/.Audio plugins end up /Library/Audio, fonts go into /Library/Fonts, and the bulk of Application libraries into Application Support Things like Fonts, Audio plugins, support libraries for applications (Such as the Adobe CC suite), and assets for Final Cut Pro end up in this folder. /Library - This is the global library accessible to all users.To run macOS, you need this, and Apple protects its users from tampering with the /System. Under modern macOS this resides on a separate partition that isn't manipulatable by the user.

/System - This is where macOS itself resides.Hint: Tilde (~) indicates the home directory of the user, this is a *nix convention that macOS carried over. This is confusing as there are at least two Libraries on your computer and more if you have multiple users on a single computer.

System Data is the tally of the contents of the following:Īll these can be managed by the user with /System being the outlier. Why this difference is so large or why this difference even exists at all is not explained. One user might have 'System Data' that is is only 10 GB and another might have 250 GB. This isn't because these individuals are incapable, rather that Apple does not clearly communicate what is happening nor give you any meaningful course of action.

editing cache data but thats not it this time and I can't figure it out)'. I see pretty frequently posts on Reddit posts like ' Can someone please explain how to get rid of the 'sYsTeM dAtA' this?' or hyper verbose ' Why do I have 130 gigs of system data 💀 (and how do I get rid of it cause a normal mac barely has like a 20 gigs or so of system memory) (I checked the usual culprit i.e.

How to clear out disk space on mac