MacBook Air storage full due to 165 GB /System directory

Respectfully

A 256 GB SSD Capacity SSD drive in 2026 is equipment to when Apple sold the big 128 GB Capacity SSD Drives

As Others have mentioned, the mount point of /System/Volume/Data is where your User Account ( Home folder ) is located

Reducing System/Volume/Data is a common question. 

Not easy to deal with or give a definitive answer on how to reduce it

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

4 - Running out of storage - system data is huge after upgrade to macOS Tahoe 26.2

How to free up ‘System Data’ and other storage on your Mac from a fellow colleague  @ neuroanatomist

Use another application to see where space is being used  Storeograph  Directly from the Developer 

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.

What’s tripping you up here is how modern macOS (APFS + sealed system volume) presents the filesystem. /System is not a normal directory anymore, it’s a mount point that exposes multiple volumes, including the writable Data volume via firmlinks.

When you run ** from /, it often double-counts space because /System/Volumes/Data mirrors large parts of the filesystem (like /Users, /Applications, etc.). That’s why you saw /System reporting 165 GB even though the real usage elsewhere was much smaller.

The clue is in your own output: /System/Volumes/Data was only ~55 GB, which means the rest was just the structure of mounted volumes plus things like APFS snapshots. Those snapshots (from Time Machine) live outside the normal directory tree and can easily eat tens of GB while appearing as “System Data.” Deleting that 80 GB snapshot is exactly why the space came back.

For future diagnosis, the commands that actually reveal the truth are tmutil listlocalsnapshots / and diskutil apfs listSnapshots /- they show the hidden snapshot storage that ** can’t explain but Storage Management lumps into “System Data.”

"System Data" means things belonging to the system, and everything Spotlight cannot categorize.

The /System directory contains Volumes which includes mount points to the various OS volumes, but also has a mount point to the Data volume. Try:

** -sh /System/* 2>/dev/null | sort -h
** -sh /System/Volumes/* 2>/dev/null | sort -h

Zedairder wrote:

I deleted 80 GB from a Time Machine snapshot. I only had one. It was really big. It wouldn't delete from terminal so I had to find it in disk utility. I think it's because my iMac that I use for back ups is on an old OS.

Thank you for the follow-up 👍

Does this now mean the current issue seems resolved ?

Not to harp on this issue and happy computing

🦉-53

You may consider your Options, moving forwards

Just saying

It was my pleasure making your acquaintance

When is the last time that you:

Backed up to Time Machine?

Cleared streaming caches?

Cleared browsing data?

Restarted your device?

What does spotlight have to do with this? I'm a bit confused there still seems to be things missing

The storage display (where you saw System Data was 124GB) is all generated by Spotlight. Each file is placed into a category by Spotlight, Documents, Applications, Music, etc. If Spotlight cannot determine which category the file belongs, it gets lumped into "System Data."

It’s really difficult to try to figure out storage on your own. The file system is recursive. /System actually includes almost the entire hard drive.

The only thing you can really do is look at “free” storage in Disk Utility. Ignore anything that says “available”. That category doesn’t actually exist.

Life won’t be easy with a 250 GB hard drive. While it’s hard to see from what you’ve posted, it appears that you are doing exceptionally well compared to other 250 GB drives.

Zedairder wrote:

Well I have 100 MB free…

That's about what I would expect.

what the **** is the point in having the 250 gb option if I can only store 80 gb of data?

That's just the way these things work. They sell computer with options. You pick the options. Don't pick the cheapest option - ever.

literally nothing I can do. I want to use my iMac as an external drive but it's useless because I would have to save it (temporarily) to the MacBook drive to actually use the files I save on the iMac. it was literally never like this before… I've usually always had 90 gb free there has to be a fix

Don't waste your time with any of that. Just get a new computer.

Follow on

And Yes, Apple still sells the Stock M4 MBA with the 256 GB Capacity Drive

The only real change, is they have Upped the Ante on the Unified RAM from 8GB to 16 GB