"System data" is taking up nearly 1TB of hard drive space

I recently started getting system warnings about running out of space, so I deleted some stuff and moved some stuff to an external drive. But the warnings kept coming, so I checked the Storage tab in "About this Mac," and it turns out that nearly all of my iMac's internal drive space is being used by "System data," which is bonkers!


I've googled the issue but none of the articles I've found were at all helpful to my situation. And it gets even weirder: I checked the total amount of space that's in use by the each of the four root directories on my internal drive:


  • Applications 56.27 GB
  • Library 133.12 GB
  • System 17.64 GB
  • Users 35.98 GB


This adds up to 243.01 -- not even remotely close to my drive's total space usage! So I assume there must be some invisible directories in there. Can I make them visible? And more to the point, how can I fix this??

iMac (M1, 2021)

Posted on Oct 5, 2023 4:54 PM

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Posted on Oct 10, 2023 1:58 PM

It's tough to tell since Apple now hides so many files, logs & caches are two things that can grow beyond belief, and the Storage Report is of no help usually.


Some things to look at, let usc know one way or the other please.


You may find neuroanatomist's User Tip helpful: What is "Other" storage on a Mac, and how can I clean it out? - Apple Community. 


Terminal code to clean DocumentRevisionsfolder…

https://apple.stackexchange.com/questions/313102/what-will-occur-if-the-documentrevisions-v100-folder-is-deleted

macos - What will occur if the .DocumentRevisions-V100 folder is deleted? - Ask Different (stackexchange.com)


Look for iOS backups…

/Users/YourUserName/Library/Application Support/MobileSync/Backup


OmniDiskSweeper shows you the files on your drive, largest to smallest, and lets you quickly Trash or open them.

https://www.omnigroup.com/more/


Purging local backups

Please note that although this doesn't affect your remote backup from Time Machine, this will get rid of the redundancy (at least until the next Time Machine backup) that a local backup disk will provide. If you need such redundancy or are worried about the recovery of your data then you would be best served to let macOS determine when to purge these files.

Start Terminal from spotlight.

At the terminal type tmutil listlocalsnapshotdates. 

Hit enter.


Here, you'll now see a list of all of the locally stored Time Machine backup snapshots stored on your disk.

Next you can remove the snapshots based on their date. I prefer to delete them one at at time. Once my "System" disk usage is at an acceptable level, I stop deleting but you can delete all of them if you want to reclaim all of the disk space.


Back at the terminal, type tmutil deletelocalsnapshots YYYY-MM-DD-HHMMSS , where will be one of the dates from your backup. This will be in the form of xxx-yy-zz-abcdef. Try to start with the oldest snapshot.

Hit enter.

Repeat for as many snapshot dates as required


http://www.thagomizer.com/blog/2018/03/27/cleaning-up-time-machine-local-snapshots.html


tmutil deletelocalsnapshots / # deletes all the snapshots


Thanks to BobHarris file sizes, Applications -> Utilities -> Terminal:...


sudo du -hx | sort -h 


sudo du -hx ~/| sort -h 



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"System data" is taking up nearly 1TB of hard drive space

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