My Mac shows a large amount of storage being used by “System Data,” but I cannot find out exactly what files are taking up the space. I have checked the storage settings and removed some unnecessary items, but the usage remains high. I want to understand what is included in System Data and how I can safely identify or reduce it without affecting my Mac.
System data covers a number of things but one common one is time machine snapshots, if it doesn’t have the target location available to backup to it just starts stacking snapshots locally.
You can check if you have time machine enabled and if you do it can be disabled if your not really using it.
App cache also can build up over time and I think falls under system data
One useful tool might be mole which is a open source optimiser / cleaner GitHub - tw93/Mole: 🐹 Clean, uninstall, analyze, optimize, and monitor your Mac. Free open-source CLI, plus a native Mac app. · GitHub
You can install via brew if you want to use it