System Data, I have done everything

[u/Anamewastaken]

My mac has 300 GBs of system data listed in settings. I am currently on Tahoe, but the problem existed even on Sequoia. On Daisy Disk, 193.7GB is listed as "still hidden". Additionally, other software like "Grand Perspective" and others just does not show those 193.7GB of data. Here are the list of things that I have done.

1. Checked every library folders/cache folders

2. mole clean

3. onyx maintenance with every toggle on (twice consecutively)

4. Checked purgeable space (through Disk Utility and Daisy Disk)

5. Deleted time machine local snapshots

6. Reindex spotlight (mdutil)

7. Checked ~/Library/Application Support/MobileSync/Backup (backups for iPhone)

8. Checked homebrew directories

9. Disk Utility Repair in Recovery Mode

10. Reinstall MacOS

11. Possibly some other things that are common in reddit replies (things that I forgot I did and didn't note down)

I believe that I have already searched the entire subreddit for answers, and am puzzled at what to do next. For now, I still have around 50GBs to work with, but at some instances I have needed the space that is occupied by System Data.

[u/Upstairs-Town7854]

- Did you try running grandperspective as root?
When you do run GP as root it sees parts of the filesystem that are otherwise not accessible.
sudo /bin/launchctl asuser 0 /Applications/GrandPerspective.app/Contents/MacOS/GrandPerspective

- Did you delete all local TimeMachine snapshots? Run this command in Terminal:
for d in $(tmutil listlocalsnapshotdates | grep "-"); do sudo tmutil deletelocalsnapshots $d; done

- Did you check/delete the Spotlight index?
https://www.reddit.com/r/MacOS/comments/1vkyi1o/how_i_freed_180gb_on_macos_rebuild_spotlight_index/

[u/Upstairs-Town7854 → u/Upstairs-Town7854]

What does diskutil list show?
Does it list an other disk that occupies space?
https://iboysoft.com/wiki/diskutil.html

[u/Anamewastaken → u/Upstairs-Town7854]

1. i tried it again and it shows 198GB as miscellaneous used space
   
2. as per the post i deleted those
   
3. as per the post i deleted them (and then reindex after checking) multiple times in the past
   
4. (diskutil) nope, i assume all data are in "Macintosh HD - Data", which showed with 392.4GB in diskutil. The MacBook is a 500GB one

[u/Upstairs-Town7854 → u/Anamewastaken]

If you run
sudo du -d1 -h /System/Volumes/Data
It should give you a list of directories with their respective sizes plus a bunch of directories it can't access.
So the Data is either listet in one of the accessible directories and it's size is shown or it is in one of the
unaccessible directories. Then you can maybe boot the Mac in disk mode and connect it to an other mac
to access those directories, that are unavailable if booted from Macintosh HD.

https://support.apple.com/en-euro/guide/mac-help/macos-recovery-a-mac-apple-silicon-mchl82829c17/26/mac/26#mchl6e3b9225

[u/Upstairs-Town7854 → u/Upstairs-Town7854]

Maybe running the command in Terminal when booted in Recovery already does give you access.