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

[ahostmadsen]

I deleted a 20Gb iPad backup through 'about my Mac.' One would think that should give me 20Gb extra space. What I got instead was exactly 0Gb extra space. Did I misunderstand elementary school math? I don't understand how to get more free space if deleting files results in no extra space.

It seems MacOS has a very opaque way of managing space.

 

[TiggrToo]

I deleted a 20Gb iPad backup through 'about my Mac.' One would think that should give me 20Gb extra space. What I got instead was exactly 0Gb extra space. Did I misunderstand elementary school math? I don't understand how to get more free space if deleting files results in no extra space.

It seems MacOS has a very opaque way of managing space.

Did you empty the trash?

Also, was it really 200GB or just reporting 200GB (e.g. a sparse file). Also it could have been a hard link and not the final file.

 

[casperes1996]

Did you empty the trash?

Also, was it really 200GB or just reporting 200GB (e.g. a sparse file). Also it could have been a hard link and not the final file.

There’s also APFS snapshots to consider. A local backup of the computer’s prior state can exist

 

[TiggrToo]

There’s also APFS snapshots to consider. A local backup of the computer’s prior state can exist

Ain’t computers great! When is a file not a file??

 

[casperes1996]

Ain’t computers great! When is a file not a file??

Procfs and devfs are looking worried in the corner now, haha

 

[Nermal]

If you go to About This Mac and check the storage tab, you may find that the free space is showing in there. It seems to take some time for Finder to update.

 

[ahostmadsen]

Did you empty the trash?

Also, was it really 200GB or just reporting 200GB (e.g. a sparse file). Also it could have been a hard link and not the final file.

I deleted it through 'about my mac' which does not send things to the trashcan (and just to make sure I emptied the trashcan). One would assume that Apple's utility knows how to delete a file completely.

 

[ahostmadsen]

There’s also APFS snapshots to consider. A local backup of the computer’s prior state can exist

Yes, I read about this. How long does it keep that copy? I did an actual TM back to my backup disk, and I would assume then it deletes the local backup. But still I gained nothing.

 

[ahostmadsen]

If you go to About This Mac and check the storage tab, you may find that the free space is showing in there. It seems to take some time for Finder to update.

Unfortunately, about this mac also shows no extra space.

 

[casperes1996]

Yes, I read about this. How long does it keep that copy? I did an actual TM back to my backup disk, and I would assume then it deletes the local backup. But still I gained nothing.

Doesn't matter that you did the TM backup to disk. The idea is that if you bring your computer away from your TM backup, you can still access backups to some degree.

I'm honestly not entirely sure about retention but it should be marked as "purgeable" space. - So it's not per se free, but if you're actively trying to use the space it should just transparently make it available.
You can also manually inspect and purge the snapshots.
To list you Time Machine made APFS snapshots you can use this

To just generally query the disk about APFS snapshots you can do

 

[BrianBaughn]

I'm thinking the problem is that in most circumstances, by default, users don't have control over the storage in macOS…due to Photos and other iCloud document syncing as well as backup management.

 

[ahostmadsen]

If I were a conspiracy theorist, I would say this is a plot by Apple to make you buy larger drive space. The amount of storage used can only go one way: increase. It is impossible to decrease the amount of space used on a drive!

 

[Boyd01]

I would check again later. In Catalina I noticed that changes in free space were not always reflected immediately. 20gb (not 200gb!) is pretty small. A year or so ago, I deleted a few hundred gigabytes and was not seeing any change in free space. After messing around for awhile, I gave up. When I checked again after awhile, the free space was finally shown.

I don't buy your "conspiracy theory". That would not be very smart if a company is trying retain customers.

 

[ahostmadsen]

I would check again later. In Catalina I noticed that changes in free space were not always reflected immediately. 20gb (not 200gb!) is pretty small. A year or so ago, I deleted a few hundred gigabytes and was not seeing any change in free space. After messing around for awhile, I gave up. When I checked again after awhile, the free space was finally shown.

I don't buy your "conspiracy theory". That would not be very smart if a company is trying retain customers.

That was a joke: I used ‘were.’ I am not a conspiracy theorist.

 

[macsound1]

I do agree that while some of the functionality of APFS and macOS that allow you to duplicate files without actually making another copy that saves space is nice, it is overly convoluted how storage space is actually used on your device.

Also, while versioning of files is also nice and file size would be relatively small on something like a word document, there isn't alot of transparency about how versions and local TM snapshots work.

It almost should be below the file name or in the title bar when the file is open.
Something l like: "256kb document, with 8 versions 1.3MB"

 

[ahostmadsen]

I would check again later. In Catalina I noticed that changes in free space were not always reflected immediately. 20gb (not 200gb!) is pretty small. A year or so ago, I deleted a few hundred gigabytes and was not seeing any change in free space. After messing around for awhile, I gave up. When I checked again after awhile, the free space was finally shown.

I don't buy your "conspiracy theory". That would not be very smart if a company is trying retain customers.

But the serious part of the 'conspiracy theory' is this: my drive is running low on space. I'm pretty sure a lot of stuff on the drive is junk, wouldn't be surprised if it's more than 100Gb. So, I use 'About this Mac' to delete some of the junk, but I get no more free space. The end result is that the only solution is to upgrade from a 512GB drive to 1TB drive. No, Apple does not do that on purpose to scam customers, but it's still uncomfortable that the space management is so opaque. As a customer you have no way to make an informed decision if you should get the bigger drive.

 

[NT1440]

Really dumb question here....have you rebooted? Maybe run first aid in Disk Utility so it re-indexes?

 

[ahostmadsen]

Really dumb question here....have you rebooted? Maybe run first aid in Disk Utility so it re-indexes?

Yes, thanks, I did in the hope that would free my space; no luck. The computer is one week old, so one wouldn't think first aid should be needed.

Here is another theory (and since the space management is so opaque, one can really only guess). Apple tries to keep around 10% space as free. As weak evidence: I have two MacBooks that have identical software and data (synced through Dropbox/iCloud), but are not copies of each other. For example, this 20Gb iPad backup was on only one computer. Yet, they both have around 50GB free.

 

[casperes1996]

Yes, thanks, I did in the hope that would free my space; no luck. The computer is one week old, so one wouldn't think first aid should be needed.

Here is another theory (and since the space management is so opaque, one can really only guess). Apple tries to keep around 10% space as free. As weak evidence: I have two MacBooks that have identical software and data (synced through Dropbox/iCloud), but are not copies of each other. For example, this 20Gb iPad backup was on only one computer. Yet, they both have around 50GB free.

How do you measure free anyway? Do you include purgeable storage? Anything purgeable is still "available to use" but is not free here and now

Did you try checking for snapshots?

 

[ahostmadsen]

How do you measure free anyway? Do you include purgeable storage? Anything purgeable is still "available to use" but is not free here and now
View attachment 1793690

Did you try checking for snapshots?

How to you see purgeable space? The free space I report is what both 'About my Mac' and Finder gives me; they don't say anything about purgeable space. I know you can check for snapshots with tmutil, but how can you see the size of them? Thanks

 

[ahostmadsen]

OK, I found it in diskutil. It tells me purgeable space is 0. So, again that makes it more of a mystery where those 20GB went.

 

[rpmurray]

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

 

[casperes1996]

How to you see purgeable space? The free space I report is what both 'About my Mac' and Finder gives me; they don't say anything about purgeable space. I know you can check for snapshots with tmutil, but how can you see the size of them? Thanks

There's not per se an easy way to do this, since it's deltas not entire file sections in the local snapshots.

But this person on Reddit has a little thing that gives you delta drift
https://www.reddit.com/r/MacOS/comments/f8ducl
Your path would be somewhere under like /Volumes/com.apple.TimeMachine.local/Backup.backupdb/computerName
or something like that

Command can take quite a while to run, btw
You get an output similar to this thought I can't vouch for its accuracy. It feels like too much in my case

 

[casperes1996]

Yeah, no, I dunno what went crazy when I ran it there but that was definitely not the proper sizes. After deleting them, since I have the TM Backup proper anyway, I only regained 60GB

I dunno, play around with it a bit. You can also use the tmutil thinlocalsnapshots (if memory serves that's its name at least) to not outright delete your local snapshots but just thin them by some amount, which will follow the same behvariour the system would use if it were so low on disk space it'd automatically start killing off old backup data locally.

I of course also can't guarantee snapshots have anything to do with your issue at all

 

[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

I have been using OmniDiskSweeper. But that also gives odd results: it tells me my photo library is 0GB, while it's 200GB according to Finder.

Here is another way to calculate my usage. I have 200GB in my photos library, 40GB in my Dropbox, and 60GB in Applications, total 300GB. How much space does Big Sur itself take up? 20GB? That leaves 180GB that should be 'free.' But I only have 50GB free. So, there must be 130GB that is various degrees of junk.