MacOS Sequoia filling up with system data

I have 15.2 installed. I had an unusually large amount of data in system that cannot be explained. The last time I checked it was closer to 33gb. I chunked the library folders and discovered that messages showed 46gb and iCloud Drive showed 52gb. in the storage section of the Mac iCloud Drive showed 23mb and messages showed 3gb. Those outliers are what the system data is using. Cache was closer to 2gb so deleting those files is pointless. moved the messages folder on a separate HDD and deleted that library file which resulted in all my messages removed. they can be restored from iCloud. the iCloud Drive file is not removable. you can turn off iCloud Drive and restart the computer but there was no change in the file size.

This is a bug and should be reported and a ticket submitted asap. Call don't message. get it done right

I have been having the same problem as well. Both Mac OS and system data were bloated. Mac OS registered at 41GB while system data registered at 281GB. My software was the earlier version of Sequoia.

I had a call with apple support earlier in the day we couldn't resolve it either and he mentioned that my Mac OS should not be at 41GB and should only be in the 20s territory.

I just upgraded my software to 15.3. Mac OS is now at 21.84GB and System storage is down to 183.98 GB (still high, but definitely decreased from the 281GB).

Hope this helps.

I have found that one can boot into recovery on the Mac, erase the drive and reinstall the OS which will reset the system data file much lower but will again increase over time. I have done this on 3 Macs and works every time.

Since macOS Sequoia, there is a way to link files and folders similar to a hard link that is only available for macOS. This is called a "firm link". Such "firm links" cannot be created by the user. These "firm links" are used to link the user-writable folders on the boot disk to /System/Volumes/Data. Apparently, the built-in terminal tools such as 'du' or 'df' as well as the third-party desktop app 'DaisyDisk' cannot yet handle these new "firm links" correctly in every case and the disk space for the linked areas may be counted twice. This mainly affects the content of /Users, /Applications and /opt

Spotlight or more precisely mds_stores is writing huge amounts but they are disappearing instantly and NOT filling up my drive.

However it is still creating immense wear which will eventually destroy my SSD.

The only "cure" I have found is to drag all my drives into the "do not search" box of Spotlight in System Settings.

This has reduced the total writes from over 100 GB per day to a normal 12 GB daily but of course it means Spotlight won't work.

I've never found it to be much good so I am not too bothered by its loss but it would be nice to have a fully functional machine even though I don't need it.

This has become a huge problem for me. I have 3 Mac's and all of them have had this issue since updating to Sequoia. I have a new Mac Pro that is 3 months old with a 1TB harddrive and the System Data has been growing every day. It got to 600GB and I loaded an older version of the machine in and watched the system data. It just seems to grow unchecked until I run first aid. This reduces the system data down to less than 1GB of space. Over time it grows. Right now it is 383GB and it has been 5 days or so since I ran first aid on the hard drive. HELP from someone from Apple would be helpful.

Have noticed this on 3 different computers, all running latest Sequoia 15.2 (iMac 27" 2020, MacBook Pro 16" M2 Max, and MacBook Pro 14" M3 Pro). Even with internet off, so no connection and at all and all Apps closed off so nothing is "running", I can sit and watch the drive space disappear. Have tried safe boot on all 3 computers, but even in safe boot on all 3 you can sit there and watch the space disappear in front of your eyes. Albeit in small "MB's" amount (may only be 1-2MB at a time), but it will keep disappearing.

In a 10 minute space I saw it go down from available space of 657.78GB available to 657.55GB (it just went down to 657.54GB as I typed the above) available.

Only just upgraded one of the laptops to Sequoia yesterday which was when I started noticing it more. Then looked at the others to see as well. Very strange.

I stumbled across a fix for my system data problem that you all seem to be having too.

The crazy thing is that I didn’t do anything other than locate the folder in the library that stored the nearly 1 TB of system data…and it’s somehow all good now. 

Here is exactly what I did:

-Open finder -> Go -> Library -> View -> View Options -> “Calculate All Sizes” option -> Sort the Library by Size.

When I viewed the Library sorted by size, and when calculating all sizes was turned on (which shows the size of the folder and all subfolders in it), then it showed the largest folder clocking in at more than 1 TB total. That folder is the “Group Containers” folder. When I double clicked this folder to check out what’s in there, it became clear immediately that I didn’t understand what I was looking at, so I didn’t touch anything in there and I went back. 

I don’t understand what happened next, but the Group Containers folder immediately went down from being more than a TB to about 82 GB. 

Then when I went to look at my storage info in system settings, it showed the system data folder had shrunk just as much as the Group Containers folder had just shrunk. I don’t get it, but it’s fixed and that’s how it happened.

Credit to this YouTube video that I didn’t even finish watching because it fixed itself at basically step 0 of the video.

https://youtu.be/9P4oqri4dYc?si=_o81P9CmOg5sUYmY

Hopefully it works for you all too!

edit: I have a MacBook Pro M4 (my first Mac computer ever).

What you did was to reindex Spotlight. You can also follow this process:

Rebuild the Spotlight index on your Mac - Apple Support

For me, Spotlight index is the culprit. I followed this article and reclaimed ~400GB of space.

It seems that the hidden Spotlight index folder which does not report its size to Finder is consuming excessive amount of space.

[Edited by Moderator]

System Data is not a real thing. It's a calculated estimate of "everything else / unknown".

When you access the Storage page of Settings it tries to calculate across the entire drive the kinds of things that are using up space. I suspect it's using Spotlight data for the categorisation. So it gives you a bunch of data it's found of known common types, like Applications, Documents, Music, Photos. Then it counts up stuff sitting in other users accounts and the /Users/Shared folder.

Finally, it just calculates the remainder: total disk space remaining, minus everything it could account for --> "System Data".

The label is a guess at best, and misleading at worst. It should be labelled "Everything else / don't know".

The hint's in help page for that field: "Contains files that don't fall into the categories listed here".

I just wanted to clarify that for other readings, like myself, coming here trying to understand why it's so large.

In my case I've supposedly got 783GB of System Data, and none of the other examples discussed so far offer an explanation of what it's made up of. The modern Mac is a Pandora's box of inaccessible magic links. It seems designed to prevent us from understanding it. Very frustrating.

So if turned off Desktop and Documents and Photos and off loaded them to a external SSD you would gain 127 GB on your internal SSD and free up space on you iCloud. A win-win.

Check out the YouTube video in this thread posted by TechSiren. That helped me get 100 GB back.

You would need to erase your drive and reinstall the OS to see the storage reduced any appreciable amount.

Hi,

Your Mac “System data” contains files that don’t fall into the categories listed here (Apps, Document folders, iCloud Drive, iOS Files, TV, Music, Books, and Podcasts Mail, Messages, Music creation, photos, trash, apps and files from macOS). 

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.

You will have to navigate through your files in library to clear this " system data". I have created a video about this with steps.

You can have a look and see if you are able to follow it : https://youtu.be/9P4oqri4dYc?si=1WT4JKtmYfdnfTrd