System Data keeps growing on MacBook Air

This is a fairly common complaint here in the community and typically is related to a Mac with a low-capacity, 256 GB startup drive.

Unless you can free up a significant amount of space - 100 GB - then you will continue to have this problem. At minimum you need to keep a 50 GB free all the time for the OS to work properly.

The best way to free up space is to move all non-essential files to an external drive and erase them from the startup drive. The only files that a relevant here will by those files in your user's home folder, including in the Documents, Download, Music and Pictures folders. If this laptop is owned by your company, then you should not have any of your own personal files on the drive.

Very often, the only way to eliminate the problem is to erase the drive and reinstall macOS, as your IT folks have done once before.

NyxKit wrote:

Thanks for the reply.

You're welcome.

[...] If I doubled the size of the start up drive, would the fix the issue? or would the system data just keep growing?

If you could double the size of the startup drive it would help, I'm sure.

Unfortunately, the startup drive in the MacBook Air cannot be upgraded.

If you'd like to examine the drive to find the largest files and folders, you can use apps such as DaisyDisk from Software Ambience or OmniDiskSweeper from Omni Labs .  Once you've located these larger user files, you can relocate them to another drive and/or delete them if they aren't needed.

It may help - or it may not. Without knowing exactly why this is happening it's difficult to be precise about that.

Part 1 of 3

Generally

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

Part 2 of 3

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.

Part 3 of 3

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

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