10.15.4 misreporting SSD usage on Mac Mini

[drsox]

I have a 1TB new Mini that Disk Utility says is using 920.51GB in the -Data volume. AFAIK I'm only actually using 150GB or so.
When I saw this I deleted a set of files that were using 350GB or so but the Disk Utility usage didn't move from 920.51GB !
I started to add back the files and the available space did decrease.

So something is misreporting the space used. I rebooted etc but no change.

What should I check before I delete myself and start again from a clean base ?
Luckily I have two other Macs as well as CCC backups. All the Macs are on 10.15.4

Cheers

 

[Taz Mangus]

Do you use TimeMachine? Maybe there are local snapshots taking up space.

 

[drsox]

No

 

[joevt]

Did you try First Aid?

 

[Honza1]

Check with CCC what local snapshots you have - there is nice browser built in the CCC. You can even delete the snapshots. If you find enough space in snapshots (you should, if you deleted 350GB of data), this is normal.
This is well known behavior of Apple APFS today. Even when not using TM, local snapshots are created routinely. They stick around for 1-2 days and take up space under some conditions (mostly not). If needed, they should be deleted automatically to return space to user. They should eventually age out and be deleted and space should be returned to user.
Theoretically, user should not have to pay attention to snapshot management. And snapshots enable user to get quickly back to prior disk state (recover) if something goes wrong and deletion/overwriting happens.
Once in a while something goes wrong with snapshots and they stay around. CCC will let you delete any extra large or extra old - or just all of them if you are sure you do not need them.
By the way, CCC may be now using snapshots also, so it could be either TM or CCC leaving crum behind.