Why is my Mac clogged up with System Data and how do I remove it?

[rogercorke]

My new Macbook Air has suddenly become clogged up with "System Data", leaving me with only 3GB of the 500GB hard disc left. This seems to have happened almost overnight but, when I analyse the storage, it never tells me what this system data consists of. I know I can remove the documents and apps, wipe the hard disc and put them back again without the annoying system data, but it would remove all my settings and I don't want to spend a day putting my machine back to the way I want it.

What caused the hard disc to suddenly become clogged up and is there an easy way to remove it?

 

[Corefile]

Omni Disk Sweeper

 

[bogdanw]

If your MBA is on Sequoia, a part might be Apple Intelligence. Check the size of folders in /System/Library/AssetV2
https://forums.macrumors.com/thread...27-gb-of-disabled-apple-intelligence.2455227/
https://forums.macrumors.com/thread...ut-still-taking-up-5-45gb-of-storage.2448369/

 

[Boyd01]

Have you looked for time machine snapshots? Open Disk Utility (in the Utilities folder inside the Applications folder). Snapshots should be shown at the bottom of the window. You can also delete them there.

 

[rogercorke]

I have discovered what the problem is - though not the reason why. My library in iMovie had used up 126GB of storage. I hardly ever use it and, if you added up all the storage from the five films I have edited on there, you wouldn't come to more than 5GB. Still, I cleared it off and I am now back to normal. If anyone can give me any reason why I can end up with more than 100GB in my iMovie library, I'd love to know.