Disk Space Free on iMac much lower than it should be

[yungjefferson]

I'm on a 2019 iMac running Mojave with a 500GB SSD, and the amount of disk space free seems to be completely false, as if there is 100GB of ghost data hiding somewhere.

I tried using OmniDiskSweeper to get a closer look, only to end being more confused. I'm logged into my account, which (as far as I know but I dunno at this point) has access to all files and folders within the drive, so I don't know why the amount of data found on ODS is so much less than everywhere else.

I deleted the local timemachine snapshots in terminal, but that only freed up a couple GB.

Next two screenshots are from ODS:

 

[HDFan]

Trying to figure out how MacOS uses System disk space is a losing proposition. Finder often gives you disk usage numbers that are different from those given by other applications. All you can do is look at your disk useage program (I use DaisyDisk), eliminate what is obvious such as TM snapshots, and don't sweat the space used by cache and other hidden files. If you can get a disk big enough so you aren't tight on space. That way you don't worry about it. My boot disk is about 1/3 full. I deliberately configured my system that way so I wouldn't have to worry about disk 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.

 

[yungjefferson]

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.

Thank you and HDFan for your help. Just used DiskWave with invisible files shown, and these are my results:

The total Used "should" be coming in at a little over 200 GB, even less that what OmniDiskSweeper sized it to be at around 300. I feel like I'm going crazy haha 😆🔫.

The only other thing I can think of that could potentially cause issues are the symbolic links that I use to allocate more space to the internal drive and send to the 4TB external.

 

[KaliYoni]

I'm on a 2019 iMac running Mojave with a 500GB SSD, and the amount of disk space free seems to be completely false, as if there is 100GB of ghost data hiding somewhere.

I tried using OmniDiskSweeper to get a closer look, only to end being more confused. I'm logged into my account, which (as far as I know but I dunno at this point) has access to all files and folders within the drive, so I don't know why the amount of data found on ODS is so much less than everywhere else.

I deleted the local timemachine snapshots in terminal, but that only freed up a couple GB.

View attachment 2283240
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Next two screenshots are from ODS:

View attachment 2283242 View attachment 2283243

Something you might want to keep in mind is that according to the developer's own website (the last time I looked, 11 months ago), DiskWave has not been updated since 2012. A lot of things have changed in macOS since then. Also, my web browsers are warning about expired security certificates when I click on the DiskWave link given in an earlier post–which is why I did not look at the site today.

If you're interested, this is a good overview of how free space shrinks on Mac disks over time (the website is a great place for staying up to date on troubleshooting topics, as well as general technical details):

How did that update eat so much free disk space?

Have you checked how much free space is on your startup volume after the last update? Do you wonder where it has all gone?

eclecticlight.co

and

Explainer: Disk free space

Confused by this on APFS? So you should be, as it’s complicated by features like snapshots, sparse files, and the file system itself. There’s no single figure.

eclecticlight.co

plus this utility might be useful

Do you use files and folders on your Mac? Then Precize 1.9 should be invaluable

A quick tour of this unique utility, and a recommended update for it which brings control over text size, auto-updates, and more.

eclecticlight.co

 

[hobowankenobi]

Omni Disk Sweeper will only show what it has access to...same issue for every similar tool as far as I know.

The workaround is a command via the terminal:

sudo /Applications/OmniDiskSweeper.app/Contents/MacOS/OmniDiskSweeper

This is assuming you put ODS in the Applications folder. This opens the app. Leave the terminal window open, and sweep the drive as you have before. More info here.

You will still likely not see everything...but the things you want to clean/manage should be visible.

 

[Mike Boreham]

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.

Thanks for the recommendation! I really like the look of Diskwave (as you say no ridiculous graphics) but it is paralytically slow on my M2 MBA to produce the first level fully populated listing, and then when I clicked on the top item 'User' nothing happens ...it doesn't show anything at next level.

I hate the DaisyDisk graphic but it is blazing fast and the text at top right gives the info in a usable form, and very easy to right click 'run as admin'.

I would much prefer DiskWave if it worked. Is it working properly for you in Sonoma 14.4?

Thanks

PS DiskWave has full disk access granted.

PPS DiskWave website wont open due expired certificate.