Taming the Storage Monster: How to Clear "System Data" on Your Mac

If you've ever checked your Mac's storage settings only to find a massive, opaque bar labeled "System Data" (formerly "Other") eating up 50GB or more, you know the frustration. For developers especially, this category can balloon rapidly. Here is a guide on how to hunt down those hidden gigabytes and reclaim your disk space.

1. The Developer's Secret: Xcode Simulators

If you develop for iOS, Xcode is likely the biggest storage hog. Simulators for older iOS versions stay on your disk long after you've stopped using them.

The Fix:

• Open Xcode.
• Go to Settings (or Preferences) > Components.
• Scroll down to the Simulators section.
• For any simulator you no longer need, tap the (i) icon and select Delete.

2. Xcode Derived Data

Every time you build a project, Xcode generates "Derived Data." While this speeds up builds, it can grow to massive sizes over time and occasionally gets corrupted.

The Fix:

• Open Finder and press Cmd + Shift + G.
• Paste: ~/Library/Developer/Xcode/DerivedData.
• You can safely delete the folders inside this directory. Xcode will simply rebuild them next time you open your projects.

3. Clear the Library Caches

Apps store temporary data in your Caches folder. While mostly harmless, some apps (like Spotify or Adobe tools) don't always clean up after themselves.

The Fix:

• In Finder, press Cmd + Shift + G.
• Paste: ~/Library/Caches.
• Browse the folders and delete those belonging to apps you no longer have installed, or clear out the largest ones. Note: Don't delete the folder itself, just the contents.

4. Delete Time Machine Local Snapshots

If you use Time Machine, macOS creates "local snapshots" when your backup drive isn't connected. These are supposed to be deleted automatically when space is low, but they often linger.

The Fix:

• Open Terminal.
• List snapshots: tmutil listlocalsnapshots /
• If you see a long list, you can thin them out or wait for the OS to catch up. If you want to force a cleanup, you can use: sudo tmutil thinlocalsnapshots / 10000000000 4 (This asks to thin 10GB with priority 4).

5. The "Big Files" Hunt

MacOS has a built-in tool that is surprisingly effective for finding what "System Data" actually consists of.

The Fix:

• Go to System Settings > General > Storage.
• Click the (i) next to Documents.
• Use the Large Files tab to see exactly what is taking up space. Often, it's a forgotten .dmg installer or a huge log file from a runaway process.

6. Homebrew Cleanup

If you use Homebrew, it keeps old versions of every package you've ever installed "just in case."

The Fix:

• Open Terminal.
• Run: brew cleanup
• You might be surprised to find this clears up several gigabytes of old binaries.

By following these steps, you can usually shrink that "System Data" bar down to a manageable size and keep your Mac running smoothly!