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Huge System Data

Hi, I've been using my MacBook Air for less than a year, and keep getting errors that the hard drive is almost full. There are very few files on my laptop, and when I check the system storage it says that 'System Data' is 169.09GB. Trying to find the source, it seems my user folder is 185.29GB, but the only large file in there is Parallels (38.58GB). The other files are all in the MBs.


What is taking up all this space and how do I do something about it?


This MacBook only has a 250GB SSD, so it's causing problems.

MacBook Air 13″, macOS 12.6

Posted on May 7, 2023 7:11 PM

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Question marked as Top-ranking reply

Posted on May 8, 2023 12:35 AM

Manage Storage


It is generally a good computer practice to alway keep at least 15% to 20% of the Total Drive Capacity’s as Empty Space. Allowing the computer to drop below these guidelines may eventually, cause unintended consequences.


There is Purgeable Space and there is Empty Space.


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  


The links below will assist in identifying what is taking up space on the Internal Drive and provide possible ways to remove data that is under the direct control of the User ( Home Folder ) . 


Rebuild the Spotlight index on your Mac


What is “Other” storage on a Mac, and how can I clean it out?


Free up storage space on your Mac


OmniDiskSweeper Safe to use


GrandPerspective 


How to delete Time Machine snapshots on your Mac.  


Often caused if the Time Machine Drive has not been attached  to the computer and TM Backup is set to run on a Schedule. 


TM Backup will make Snap Shot on the Internal Drive awaiting the TM Backup Drive to be attached. 


Only then will the Snaps Shots be transferred to the External Drive and deleted the Internal Drive.


See used and available storage space on your Mac


Locate backups of your iPhone, iPad, and iPod touch


Notation - If the user is using a cloning software like Carbon Copy Cloner - suggest tweaking the Safety Net Feature in this software. It may be making additional Snap Shots that are not being Cloned to the Eternal Drive. If this should be the case, these Snap Shot could be using additional space on the drive 


The final word from Apple on Managing the " Other/ System Data “ Category


Other / System Data: Contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.

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10 replies
Question marked as Top-ranking reply

May 8, 2023 12:35 AM in response to NewVoiceMail

Manage Storage


It is generally a good computer practice to alway keep at least 15% to 20% of the Total Drive Capacity’s as Empty Space. Allowing the computer to drop below these guidelines may eventually, cause unintended consequences.


There is Purgeable Space and there is Empty Space.


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  


The links below will assist in identifying what is taking up space on the Internal Drive and provide possible ways to remove data that is under the direct control of the User ( Home Folder ) . 


Rebuild the Spotlight index on your Mac


What is “Other” storage on a Mac, and how can I clean it out?


Free up storage space on your Mac


OmniDiskSweeper Safe to use


GrandPerspective 


How to delete Time Machine snapshots on your Mac.  


Often caused if the Time Machine Drive has not been attached  to the computer and TM Backup is set to run on a Schedule. 


TM Backup will make Snap Shot on the Internal Drive awaiting the TM Backup Drive to be attached. 


Only then will the Snaps Shots be transferred to the External Drive and deleted the Internal Drive.


See used and available storage space on your Mac


Locate backups of your iPhone, iPad, and iPod touch


Notation - If the user is using a cloning software like Carbon Copy Cloner - suggest tweaking the Safety Net Feature in this software. It may be making additional Snap Shots that are not being Cloned to the Eternal Drive. If this should be the case, these Snap Shot could be using additional space on the drive 


The final word from Apple on Managing the " Other/ System Data “ Category


Other / System Data: Contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.

Oct 30, 2023 7:54 PM in response to Anthony Glaser

Update - a few months later and System Data was up to over 400GB. Back to Apple online chat, back to senior technical support, ended up with a supervisor of senior technical support, who told me that this is a common problem which has been known for about 10 years but nobody has come up with a way to prevent it. He advised me to completely wipe my computer and reinstall everything, which I did after making backups on an external drive and with Backblaze. At the end my System Data was back down to 40GB, but I have lost 10 years of emails - they seem not to have been copied to the external drive, can't be found on Backblaze, and I can't even retrieve them from my last Time Machine backup from May (I thought have 3 separate backups would be enough, but apparently not). And a week later my System Data is back up to 150GB and tech support will not return my calls. I have been buying nothing but Apple computers since 1986 but am beginning to think it is time to change if I cannot find a way to run a functioning computer (I have an M1 MacBook Pro, with 1TB or storage that gets completely full when the System Data reaches about 400GB or so).

Jul 27, 2023 4:33 PM in response to krifos

If you have the same problem that I had a couple of months ago (which sounds likely), then all I can recommend is what worked for me. I started an online chat session with Apple about this, and within 5 minutes I was set up with a senior tech support guy who spent an hour and a half with me on line, holding my hand through a large number of (to me) complicated steps that I do not really understand, with the net result that my System Data dropped from 400 to 41 GB. He said anyone with this problem should reach out to Apple as there is no app, utility, or other ready-made answer, as every case will be individual. We still don't know quite what caused my System Data to get so huge, but at least (for the time being) the problem is solved. By the way, I do not have Apple Care and my 2021 MacBook Pro is of course long out of warranty

Huge System Data

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