How to Clear 'System Data' on macOS

What Actually Is "System Data" on macOS?

In macOS System Settings > General > Storage, the colored bar often shows a massive grey or dark grey block labeled System Data (formerly called "Other"). It is common to see System Data consuming 60 GB, 120 GB, or even 200 GB+ on a 256GB or 512GB MacBook.

Apple classifies any file that doesn't fit into standard categories (like Applications, Photos, Music, or Documents) as "System Data". In practice, System Data is overwhelmingly composed of:

Time Machine APFS Local Snapshots: Frozen restore points stored directly on your internal SSD when an external backup drive isn't connected.
Application Support & Caches: Massive caches from Spotify, Chrome, Slack, Discord, and Adobe Creative Cloud hidden in ~/Library/Caches and ~/Library/Application Support.
Developer Residue: Xcode build archives (DerivedData), iOS simulator images, and package caches from Homebrew, Docker, and npm.
macOS Sleep & Swap Images: Kernel virtual memory swap files written to disk when physical RAM is exhausted.

How to Manually Clean System Data (Step-by-Step)

Step 1: Delete Hidden APFS Local Snapshots

Time Machine frequently creates hidden disk snapshots before updates or when backup drives are unplugged. Check and purge them via Terminal:

# List existing local snapshots
tmutil listlocalsnapshots /

# Delete a specific snapshot (replace DATE_STRING with actual snapshot name)
tmutil deletelocalsnapshots 2026-09-12-104522

Step 2: Clear Bloated User Caches

Third-party applications dump gigabytes into user caches that are never purged automatically:

# Navigate to User Caches
cd ~/Library/Caches

# Inspect largest folders
du -sh * | sort -hr | head -n 10

Step 3: Remove Archived Diagnostic Logs

Crash reports and diagnostic telemetry accumulate endlessly in system logs:

rm -rf ~/Library/Logs/*
sudo rm -rf /Library/Logs/DiagnosticReports/*

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Frequently Asked Questions

Will deleting System Data delete my personal files?

No. System Data consists of cached data, local snapshots, and temporary working files. Your documents, desktop files, photos, and personal media remain completely untouched.

Why does System Data grow back after cleaning?

Apps constantly generate working caches as you browse or render media. Running XrayMac once a month ensures caches are cleared before they balloon past 50GB.

Can I delete System Data without third-party software?

Yes, through the manual Terminal commands detailed above. However, XrayMac provides a safe visual interface to ensure you don't accidentally erase active app databases.

How to Clear 'System Data' on macOS (Sonoma & Sequoia)