How come deleting a 20Gb file gives me 0Gb extra space?

[ahostmadsen]

The Finder and macOS are a steaming pile when it comes to determining the amount of free space on a drive formatted in APFS. What you need is to use an app like DaisyDisk that is written by actual professional programmers instead of the amateur-hour stuff that Apple foists on us. I mean how long has APFS been out and they still can't get something like this right?

Where did all that free space go on my APFS disk?
Quantum computing and APFS: free and used space

Here is what DaisyDisk says:

So, diskutil says 0GB purgeable, while DaisyDisk says around 40GB. Not sure what to believe. If I believe DaisyDisk, I'm not really low on disk space, in reality I have like 110GB free (free + purgeable + known junk - for example I can see I have to installations of LaTex, each taking up 5GB, a lot temporary files etc.). I could of course start to delete stuff, but the 50GB officially free should be enough for now.

 

[ahostmadsen]

And suddenly... 80GB available! I did not ask DaisyDisk to purge any space; macOS must have decided to do it by itself. The 80GB fits with the 20GB iPad backup and a few other things I deleted.

Of course it's great I now got the space. BUT. Apple is supposed to be user friendly. It is not user friendly that it takes several days from you ask the system to delete something until it actually deletes it (meaning: releases the space).

 

[KaliYoni]

Yeah, I'm joining this party a little late...but this article discusses why APFS makes it hard for the Finder to do something seemingly so simple:
"The Storage tab in About This Mac is the most likely to be fooled by Finder Aliases, links, and the factors above."

Quantum computing and APFS: free and used space

Why measuring free and used disk space is not so simple in APFS, and which estimates you should trust.

eclecticlight.co

(that website has a lot of good information and a heap of awesome free utilities, including one I think is essential for all Mac users, SilentKnight)

 

[rpmurray]

And suddenly... 80GB available! I did not ask DaisyDisk to purge any space; macOS must have decided to do it by itself.

I'm thinking that sometimes the Finder loses track of what is free or not, and the mere act of scanning the disk is enough for it to trigger an update to its record keeping.

 

[sgtaylor5]

Yeah, I'm joining this party a little late...but this article discusses why APFS makes it hard for the Finder to do something seemingly so simple:
"The Storage tab in About This Mac is the most likely to be fooled by Finder Aliases, links, and the factors above."

Quantum computing and APFS: free and used space

Why measuring free and used disk space is not so simple in APFS, and which estimates you should trust.

eclecticlight.co

(that website has a lot of good information and a heap of awesome free utilities, including one I think is essential for all Mac users, SilentKnight)

Howard Oakley is a treasure and a gem to the Mac community. Apple should make him rich or at least very well off, with no strings attached.

Apple also should fully document APFS, for everyone's sake. How many years has it been, now? Deaf ears, that's all.

 

[ahostmadsen]

And suddenly... 80GB available! I did not ask DaisyDisk to purge any space; macOS must have decided to do it by itself. The 80GB fits with the 20GB iPad backup and a few other things I deleted.

Of course it's great I now got the space. BUT. Apple is supposed to be user friendly. It is not user friendly that it takes several days from you ask the system to delete something until it actually deletes it (meaning: releases the space).

And now down to 55GB again! 😡 The 20GB I gained have now suddenly disappeared again! I did not suddenly download or create 20GB of data. It seems to me it just wants to keep around 10% free, filling the disk with junk if there's more left.

I really don't like macOS opaque space management. How can I just randomly loose and gain 20GB? And to the point: how can I know if I need a bigger disk if no matter what I do, there is always 55GB free?

 

[Boyd01]

how can I know if I need a bigger disk if no matter what I do, there is always 55GB free?

JMHO, but if you are constantly watching your disk and worrying about 20gb of space, your disk is too small. I've never had that problem since my first SSD-based Mac in 2011. It can be painful to pay the "Apple tax" for a bigger disk, but that's what I have done.

 

[ahostmadsen]

JMHO, but if you are constantly watching your disk and worrying about 20gb of space, your disk is too small. I've never had that problem since my first SSD-based Mac in 2011. It can be painful to pay the "Apple tax" for a bigger disk, but that's what I have done.

A good point, thinking of it as an Apple tax. You're right, when I get the M2 MBP, I will just get 1TB so I don't have waste energy and time on worrying about space.

 

[ahostmadsen]

And now down to 55GB again! 😡 The 20GB I gained have now suddenly disappeared again! I did not suddenly download or create 20GB of data. It seems to me it just wants to keep around 10% free, filling the disk with junk if there's more left.

I really don't like macOS opaque space management. How can I just randomly loose and gain 20GB? And to the point: how can I know if I need a bigger disk if no matter what I do, there is always 55GB free?

And back up to 75GB! I feel it's just crazy the free space can fluctuate seemingly random 20GB. But as said above, there is nothing to do than accept it, and I already decided my next Mac will have 1TB. It is $180 extra.

 

[nobullone1964]

And back up to 75GB! I feel it's just crazy the free space can fluctuate seemingly random 20GB. But as said above, there is nothing to do than accept it, and I already decided my next Mac will have 1TB. It is $180 extra.

It was my understanding that the machine uses the snapshot instead of the actual drive to function.