Shrinking Available Disk Space

Question

Shrinking Available Disk Space

Since upgrading to macOS 10.15.6 my free disk space has been steadily shrinking.

Today I started out with 179GB free on my Mac's internal SSD.

I moved a 111.7 GB Scrivener file from my internal SSD to an external Drobo 5D3 and deleted it from the Mac's SSD

Then, I restarted the Mac. I now have only 157 GB free. This is the opposite of what should be happening. I've seen some other discussions relating to this on other Mac OS forums and the only common solution seems to be a clean install of Mac OS. I'm hoping that maybe someone here has perhaps another possible fix action. I've tried Cocktail to delete TimeMachine Snapshots, but since updating to 10.15.6 it will only thin, not delete.

Thanks for any ides/suggestions.

MacBook Pro 15”, macOS 10.15

Posted on Aug 18, 2020 10:07 AM

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Answer 1

Top-ranking reply

Kappy

Level 10

361,879 points

Aug 18, 2020 11:51 AM in response to David Stempnakowski

Time Machine doesn't play well with APFS, so I would format them using HFS+ as before. TMUTIL is still usable in the same way as before.

Time Machine Snapshots

To turn them ON: sudo tmutil enable

To turn them OFF: sudo tmutil disable

Here's a good primer about snapshots on the Mac - Working with macOS (Drive State) Snapshots. Another, similar, article has added info related to APFS snapshots - Reclaiming drive space by thinning Apple File System snapshot backups | Der Flounder.

macOS is basically a windowing system for BSD Unix that has been heavily modified by Apple. You should feel right at home with the command line.

CCC's most recent versions lets you perform your own management of APFS snapshots, if you haven't discovered that yet. It's my main backup tool. I don't use Time Machine. I've never had a lot of confidence with it since I started testing it when it was first released as a beta. It seems to break too easily for my taste. Unlike the CCC developer, Apple moves slowly when it comes to fixing things.

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Answer 2

Kappy

Level 10

361,879 points

Aug 18, 2020 10:48 AM in response to David Stempnakowski

I'm puzzled. You Storage view says you have 302GBs available or free. Yesterday you started with 179GBs. Now you have 302GBs after deleting a 112GB file. So, where is the problem?

Get Correct Storage Information

Do not use the information from the Storage section of the About This Mac dialog. Ignore the Storage information as it is typically wrong. To find out the correct information for any disk: Select a Desktop disk icon. Press Command-I to open the Get Info window and look at the topmost panel displayed. You will find the disk information displayed for Capacity, Available, and Used. If you have more than one disk/partition then repeat for each one on your Desktop.

The categories found in the Storage section of About This Mac is simply an arbitrary way of displaying files on your drive. There are no such categories actually on the drive.

Also, see What is 'Other' and 'Purgeable' in About This Mac?

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Answer 3

Aug 18, 2020 10:55 AM in response to Kappy

That's what's odd. Look at what is being shown in the Finder (158.05GB). That's also what is shown in the disk's Get Info window. Not sure where the disconnect is. Disk Util shows the same numbers as the Finder. You can't trust the storage tab all the time because it's tracking files not stored on the Macintosh HD (my Photo library, iTunes, Podcast, etc. are all stored on the Drobo). I've verified by checking those directories on Macintosh HD and they are only a few MB in size.

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Answer 4

Aug 18, 2020 11:32 AM in response to Kappy

Right now I have it booted into Target Disk mode and connected to another Mac running DU. Finding a lot of errors on multiple TimeMachine snapshots. Yes, I do have a TM disk (Samsung T5) and I also do weekly Carbon Copy Cloner clones. I'm suspecting that these snapshots are not being deleted due to their being corrupted. It used to be easy to use the tmutil command, but I think that may have been deprecated with the move to APFS? Any ideas how best to delete them via the command line would be? (I'm a former Solaris sys admin).

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Answer 5

Aug 18, 2020 1:22 PM in response to Kappy

So mounting as a disk to another system, then going in via the command line I was able to remove the snapshot files. That reclaimed about 130GB. Thanks for the links!

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