My Disk Utility shows different free space remaining on my MacBook Air running macOS Ventura

Divade wrote:

I want to know is there a way to solve this problem and what could possibly caused this problem.

You can avoid this problem by keeping a "good amount" of free storage. I haven't experienced any such problems and I keep my free storage above 100 GB.

The cause is Apple's implementation of the APFS file system. It has lots of tricks that make these kinds of storage calculations impossible. The only reliable value is the free storage at the top-most level. That is what you see reported in Disk Utility. Any 3rd party tools or your own manual calculations will always be wrong because of various ways that APFS optimizes storage.

That being said, those 3rd party tools can be useful to help solve storage problems. This is one of the few times where 3rd party tools are much more useful than Apple's own tools. Apple's approach with storage is nothing short of atrocious. It is extremely confusing in multiple ways. You can rely on Disk Utility's statement about your free storage. You can also rely on the operating system when it tells you that you've run out of free storage. Anything else that Apple tells you about storage is totally bogus.

From what you've said, you are talking about discrepancies on the order of 30 GBs or so. That is exceptionally good. I regularly see people report running out of storage with TB hard drives. Their discrepancies are hundreds of GBs in size. It sounds like you're running a tight storage ship. Good job!

The Report System, in anything other than Disk Utilities is often not as accurate as DU.

Using a third party application, developed by third party developer are equally inaccurate

Stick to using Disk Utilities to measure Used and Empty Space

There is Purgeable Space and there is Empty Space.

The two are Not One and the Same

Purgeable Space which is Controlled by the Operating System.

When the Operating Systems decides the computer needs additional Empty Space, it will move a portion of the Purgeable to Empty space

AFAIK - there is no User Actions to hasten this transition from Purgeable to Empty Space

It can day or longer before this will occur.

Divade wrote:

If, it is the APFS file system caused the difference between DU and other third-party applications in disk space reading, then is it possible that the difference is 10GB or even 30GB more?

These discrepancies can come from multiple different sources. There is no limit, not even the total size of your disk.

What has caused the disk space of my old Mac to from a maximum of 121GB to 114GB? Is the MacOS iso stored in the disk, or is it downloaded directly from apple, since every time you reinstall a system, you would need to connect to the internet.

Not sure I understand your question. It sounds like you are asking about the maximum storage available in some unknown older operating system as compared to now. I have no idea. The operating system does take some space on the hard drive. And the convoluted way it is installed is sure to confuse anyone who looks at it. Plus, the operating system typically installs using low-level compression, which may not be reflected in various system interfaces when you are manually trying to add things up.

The operating system definitely knows how much truly "free" space is available. The "free space" value reported by Disk Utility is correct. Don't assume that any other storage value is accurate.

If one were to Format the Entire Physical SSD Drive in APFS / GUID or macOS Extended Journaled / GUID

Then, Stop at that point

Check the difference between 128 GB Drive Capacity and the Available Space on the drive even Before you reinstall the Operating System

I am pretty sure you will see that, although the drive is listed as 128 GB Capacity

The available and usable space will not match

The Partitioning & Formatting of the drive Occupies some Space

If you want to understand the disk layout the macOS uses, this article might be of interest to you, in addition to the article PRP_53 recommended:

https://eclecticlight.co/2021/12/16/boot-disk-layout-in-macos-monterey/

which should still be the same in Ventura and Sonoma.

Beyond that...reading through the thread I'm confused as to what you want. The raw disk loses space to partitioning. Installing the OS results in multiple hidden partitions that eat up more space (and if it's an Apple Silicon Mac, it uses even more that an Intel). Then there is the snapshot system and purgable space management...and the way APFS just works with volumes sharing container space...

As many others have said, the only accurate measurement of free space is the report of the OS itself in Disk Utility. Every other tool is hit or miss. Some are better than others - but even decent tools like DaisyDisk have limits and there is hidden space they can't read.

Divade wrote:

Bro, trust me you are not being helpful.

If the purgeable space you are talking about is some gray tile line shown in the DU, then both of my Macs do not encounter this problem at all, I am looking for a way to correct the wrong display space in the DU.

Then by all means .

Afford yourself the luxury of the suppled ⬆️ and ⬇️ arrows suppled by Apple

You are welcome

https://eclecticlight.co/2022/05/18/how-much-free-space-does-an-apfs-disk-need/

A lot of reading but also may or may not answer some of the questions

👍

Not because we agree but rather because of your good work

Too kind, mon homme!

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