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What System Data means in your Mac’s storage

What Apple says System Data holds, why you can’t clear it from Storage settings, and what does help.

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System Data is one of the categories in Storage settings. Unlike most of the others, you can’t open it to delete files. This is what Apple says about it.

What System Data holds

Apple describes System Data as files that don’t fall into any other category. It includes:

  • logs and caches
  • VM files
  • temporary files
  • fonts
  • app support files and plug-ins

macOS manages these files, so the size of System Data changes with what your Mac is doing. Apple also calls this category Other.

Source: Apple Support, Change Storage settings on Mac (opens in a new tab) and Free up storage space on Mac (opens in a new tab).

Why you can’t clear it from Storage settings

Apple says you can’t manage the contents of System Data from Storage settings, because macOS looks after it. If some of those files belong to you, such as data an app created, you can manage them in the Finder or in the app that made them.

Source: Apple Support, Change Storage settings on Mac (opens in a new tab).

macOS clears some of it for you

When space is needed, macOS clears caches and logs that are safe to delete. Apple lists temporary database files, interrupted downloads, staged macOS and app updates, and Safari website data.

Source: Apple Support, Optimize storage space on your Mac (opens in a new tab).

Time Machine local snapshots

If you back up with Time Machine, your Mac also keeps local snapshots on its own disk. They let you restore files when your backup disk isn’t connected.

  • Time Machine saves a snapshot of your startup disk about every hour, and keeps it for 24 hours.
  • It also saves one before each macOS update.
  • Snapshots are stored only on APFS disks, and only while automatic backups are on.
  • Time Machine deletes them as they get older, or sooner when the space is needed.

Your Mac counts the space that snapshots use as available storage.

Remove them now

  1. Choose Apple menu › System Settings, click General in the sidebar, then click Time Machine.
  2. Click Options, choose Manually from the Backup Frequency pop-up menu, then click Done.
  3. Wait a few minutes while the local snapshots are deleted.
  4. Turn automatic backups back on. Time Machine remembers the backup disks it was using.

On macOS Monterey 12 or earlier, open System Preferences, click Time Machine, and deselect Back Up Automatically instead.

Source: Apple Support, About Time Machine local snapshots (opens in a new tab) and About Time Machine local snapshots on Mac (opens in a new tab).

If you need space right now

Starting up in safe mode clears some system caches, which macOS creates again as needed. It can free enough space for a one-off task, such as a macOS update. The steps are in how to free up space on your Mac.

Source: Apple Support, Free up storage space on Mac (opens in a new tab).

What Apple doesn’t cover

Apple gives no steps for deleting System Data by hand. The recommendations in Storage settings and the steps above are the ways Apple documents.

Sources

Every source was checked on 11 October 2026, against macOS 27.

Disk Census looks inside the caches and logs that System Data is made of, and tells you which ones are safe to delete.

See how Disk Census works

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