How to clear system data

“System Data” isn’t a cache you can just wipe, it’s macOS grouping together stuff it doesn’t want users poking at directly, and on Sequoia it’s APFS local snapshots, VM swap files, Spotlight indexes, old installer remnants, and app support data that never got cleaned up.

The most common silent hog is Time Machine local snapshots, which don’t show up clearly in Finder and can balloon when the disk gets tight. I’d first run tmutil listlocalsnapshots / and delete older ones if they’re excessive, then check /System/Volumes/Data/private/var/vm to confirm swap isn’t exploding due to memory pressure.

If System Data is still huge, that usually means macOS is holding space hostage to keep itself stable on a small SSD, not that something is “wrong.” Reinstalling macOS or erasing the disk works because it resets snapshots and hidden system state, not because it magically optimizes storage.

The only sustainable fix is either freeing real user space or moving heavy libraries off the internal disk, chasing System Data itself is fighting how APFS and modern macOS are designed to behave.

Also, did you checked duplicate files? that would free some space for you.

ilovemangos1 wrote:

How do I clear system data?

Why is system data needed to be cleared ?

Reducing System/Volume/Data is a common question. 

1 -  System data taking too much in MacOS Sono… - Apple Community

2 - Time Machine Local Snapshot won't delete - Apple Community

3 - Over 60% storage blocked by System Data - Apple Community

Use another application to see where space is being used  Storeograph  on the Apple Apps Store 

View APFS snapshots in Disk Utility on Mac

Suggest getting an External SSD Drive and start moving your Pictures, Videos, Music and any other large files you have control over, OFF the Internal drive and Onto the External

Understanding iCloud Drive from a well written User Tip from @ Richard.Taylor

There are  two effective ways to remedy this issue:

1. Quick Fix Actions:

For Apple Silicon computers, use Disk Utility to erase a Mac.

For Apple Intel computers, use Disk Utility to erase an Intel-based Mac, then reinstall macOS.

Always make a Time Machine backup before proceeding.

Migrate only the user account, not the entire system.

Reinstall only the necessary applications from the Apple App Store or directly from the developers.

2 - Generally

When the user discovers this issue, it’s likely because the computer’s internal drive capacity is small, such as 256 GB or 512 GB.

Unfortunately, the user’s storage needs may have increased since the computer was purchased.

To future-proof the computer, consider spending extra money upfront on a larger drive capacity and adding more unified RAM.

Note - On Apple Silicon and newer computers. The SSD Drive and the Unified RAM are Soldered to the Logicboard and can not be upgraded.

to find the biggest files taking up that space, any of the Utilities mentioned in this article can help. when run as admin, they also look in hidden system directories, which Finder does not tend to do quite as well.

How to free up ‘System Data’ and other storage on your Mac

"How to clear system data: How do I clear system data?"

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Clearing System Dara on a Mac:

It takes extensive effort; but, it goes quick, after you perform it a few times. Use my User Tip: How to Use Finder to Clear “System Data" on a Mac - User Tip