Weird lost system disk space

[StormLord]

Hi
I have encountered a lot of time this weird problem in my clients Macs, and now I have it too!
I've seen it mostly on OSes that are more than 1-2 years installed and I couldn't find the reason.

As the picture shows, my 512GB boot SSD has almost 200GB data on it and it shows only 60GB free, so I have lost about 250GB and I'm unable to find where these are.
I've made sure that it wasn't TM local backups even though I'm not using TM and went to even manually show all hidden files and get directories sizes to compare.

As of now , all the times that I encountered that the only solution I've found was to backup/format/clean install and then get the back up manually back.

Anyone with a more in-depth knowledge of the OS of what might these lost space be?

 

[smirking]

Open up Disk Utility and do a Get Info on the drive. You're probably going to see all of your missing space being assigned as "Purgeable Space" that's a subset of the Available Space.

This came up in another thread recently. It appears to be a recent-ish change in MacOS.

https://forums.macrumors.com/threads/macbook-pro-m2-16-1tb-of-files-removed-but-disk-space-not-freed.2387606

That space is usable, but is not actually cleared and it's possible for some programs to not understand that space is usable.

Looks like you're another fan of Omni Disk Sweeper. That's my go to when I want something easy to tell me how much space I have on a live system. Unfortunately, it shows that purgeable space as used space.

 

[Fishrrman]

Download DiskWave from here:

DiskWave Homepage

It's small in size and free.

Open DiskWave and go to the preferences.
Put a checkmark in "show invisible files".
Close preferences.

The DiskWave window shows you all your volumes and drives in plain English (no ridiculous graphical formats).
Click on any item "on the left".
Now, you'll see what's ON the volume, listed in order of "largest to smallest".
You can easily locate what's eating up your space.

What is it?

 

[StormLord]

Unfortunately, its not purgeable space. IIRC I already tried to clean purgeable with a terminal command (that I don't remember now) and it didn't help. Also disk utility and get info does not report any purgeable space.

I'm in Mojave on a macpro3,1 but I have seen this problem over the years many-many times in different macOS versions and file systems (macos_extended and apfs)and I'm astonished that I could never find a solution for it.

 

[StormLord]

Download DiskWave from here:

DiskWave Homepage

It's small in size and free.

Open DiskWave and go to the preferences.
Put a checkmark in "show invisible files".
Close preferences.

The DiskWave window shows you all your volumes and drives in plain English (no ridiculous graphical formats).
Click on any item "on the left".
Now, you'll see what's ON the volume, listed in order of "largest to smallest".
You can easily locate what's eating up your space.

What is it?

Actually cmd-shift-. enable/disable show hidden files, don't need a utility for it
And my problem is not a file or something that takes over space, because I used few utilities and I even did it manually, and calculated sizes of ALL folders (show and hidden) and total is 200GB, so 250GB are not shown as files but this space is marked as used.

 

[smirking]

What does the built in Manage Storage utility show you in the breakdown of what all that System Data is? I'm referring to the screen that you'd get if you clicked the "Manage" button from your first screenshot.

 

[StormLord]

What does the built in Manage Storage utility show you in the breakdown of what all that System Data is? I'm referring to the screen that you'd get if you clicked the "Manage" button from your first screenshot.

as per the pic

BTW, I did carbon copy the disk to a 256GB SSD and it finished without nudging ne about disk space, I booted from it and the used space is as it should at about 200GB and 56GB free.