How do I get Disk Inventory access to the entire harddrive?

Following these questions, How can I figure out what's slowly eating my HD space?

I got Disk utility

However, after downloading it and opening it with the proper privs, it can only account for less than 20% of my entire disk usage. I have a 500gb drive, but the utility only shows 80gb of usage. Where did the other 420 gb go?

In case this is important.

Here are other things:

diskutil list:

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI ⁨EFI⁩                     209.7 MB   disk0s1
   2:                 Apple_APFS ⁨Container disk1⁩         500.1 GB   disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +500.1 GB   disk1
                                 Physical Store disk0s2
   1:                APFS Volume ⁨Untitled - Data⁩         464.5 GB   disk1s1
   2:                APFS Volume ⁨Preboot⁩                 293.2 MB   disk1s2
   3:                APFS Volume ⁨Recovery⁩                613.6 MB   disk1s3
   4:                APFS Volume ⁨VM⁩                      2.1 GB     disk1s4
   5:                APFS Volume ⁨Untitled⁩                24.0 GB    disk1s5
   6:              APFS Snapshot ⁨com.apple.os.update-...⁩ 24.0 GB    disk1s5s1

/dev/disk2 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        +248.8 MB   disk2
   1:        Apple_partition_map ⁨⁩                        32.3 KB    disk2s1
   2:                  Apple_HFS ⁨Google Chrome⁩           248.8 MB   disk2s2
                    (free space)                         132.1 GB   -

/dev/disk3 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        +326.2 MB   disk3
   1:                 Apple_APFS ⁨Container disk4⁩         326.2 MB   disk3s1

/dev/disk4 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +326.2 MB   disk4
                                 Physical Store disk3s1
   1:                APFS Volume ⁨PostgreSQL 13.3-1⁩       287.0 MB   disk4s1

/dev/disk5 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        +20.6 MB    disk5
   1:        Apple_partition_map ⁨⁩                        32.3 KB    disk5s1
   2:                  Apple_HFS ⁨Disk Inventory X 1.3⁩    20.6 MB    disk5s2

/dev/disk6 (disk image):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        +144.3 MB   disk6
   1:                  Apple_HFS ⁨inSync⁩                  144.2 MB   disk6s1

/dev/disk8 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *6.0 TB     disk8
   1:                        EFI ⁨EFI⁩                     209.7 MB   disk8s1
   2:                 Apple_APFS ⁨Container disk9⁩         6.0 TB     disk8s2

/dev/disk9 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +6.0 TB     disk9
                                 Physical Store disk8s2
   1:                APFS Volume ⁨G-DRIVE⁩                 57.9 GB    disk9s2

df -H /:

Filesystem       Size   Used  Avail Capacity iused      ifree %iused  Mounted on
/dev/disk1s5s1   500G    24G   8.2G    75%  568975 4882907945    0%   /

df -H /System/Volumes/Data:

Filesystem     Size   Used  Avail Capacity iused      ifree %iused  Mounted on
/dev/disk1s1   500G   465G   8.2G    99%  115427 4883361493    0%   /System/Volumes/Data

Tricky right? On the graphic, the System clearly says 17GB and when I go to that directory, there's almost nothing there.

I don't know how you made my screen dumps look so nice, but it's really spectacular now. Anyway, here is the result of that very long command:

Password:
49  /System/Volumes/Data/Library
4   /System/Volumes/Data/private
4   /System/Volumes/Data/System
2   /System/Volumes/Data/Users
2   /System/Volumes/Data/Applications
1   /System/Volumes/Data/usr
1   /System/Volumes/Data/home
1   /System/Volumes/Data/Previous Content
0   /System/Volumes/Data/sw
0   /System/Volumes/Data/opt

Here's the tmutil stuff:

Snapshots for volume group containing disk /:
com.apple.TimeMachine.2021-09-26-115708.local (dataless)
com.apple.TimeMachine.2021-09-26-125523.local
com.apple.os.update-A5B1E0476E2E433B92E0F2EB18AAF0644029690596503DE60EFC133B481CD52D
com.apple.os.update-MSUPrepareUpdate

Solution 1:

There are a few steps to the answer.

1. Open Disk Utility from the macOS Recovery as if you're going to do a factory reset in step 2 from this link: Erase and reinstall macOS
2. DO NOT erase the drive, unmount the drive. It's a selection all the way to the right. I'd provide a picture, but you can't take screenshots of the computer in that window. Somehow magically all the space will return
3. Remount the drive and shut down. The undetectable storage will suddenly be free. Restart the computer as is normal.

Should this not work, there is another step you can take before this failsafe.

1. Allow Full Disk Access to Terminal in the Security & Privacy of System Preferences (the gear in the rounded rectangle).
2. Install: homebrew
3. Install: ncdu
4. Run: ncdu --exclude_firmlinks /

This will do absolutely nothing, but I did do that before the macOS Recovery step and who knows, maybe it's the strong man loosening the jar before the milksop opened it.