macOS Sequoia 15.4.1 – Disk Space Rapidly Disappearing Due to System Processes on macbook pro m2

OMG. So I finally flipped the table and downloaded GrandPerspective. It very quickly and very clearly revealed a single log file in /private/var/folders taking up 85GB! It seems running the Cortex-Debug extension in Visual Studio Code quietly accumulates a massive log in the background. I hadn't used it for weeks, but it was still doing something.

I killed VSCode, did a big purge of /private/var/folders (very unclear how to do this properly, so I went carefully and thoroughly), and now, 2 weeks later, the problem has not returned. I still have 200GB free. "System Data" continues to bounce around wildly. From 101GB to 57GB and back to 101GB as I type this.

Lessons:

1. "System Data" is a very loose description. No wonder the "solutions" to this problem are so varied. The log file was obviously a user land file, but it seems even application temporary files can be "System Data".
2. The number associated with "System Data" is bizarre. Take it with a big grain of salt.
3. Storage management is just too complicated to leave to general hygiene or even the "Storage" view in System Preferences. Don't delay - get GrandPerspective.
4. VSCode extensions are the wild west - loose cannons that shoot at will.

You should try to have some more free space.

Your starting point of only some 80GB free could be the problem.

"kernel task" is a system process that is serving requests from apps and daemons, so it being using space or cpu does not by itself tell what is requesting these services.

You can test by running your mac in Safe Mode for a while - does the same problem with space occur while in Safe Mode? If not, then the problem is due to some third party software.

Please run Etrecheck and post its full report here. Use the "additional text" button and paste the report into the text box.

With dynamic wallpapers enabled, and Activity Monitor (disk write) and System Settings/General/Storage showing, I could see that every 15 seconds or so, idleassetsd would update with more data written to disk and increased System Data usage. , This would continue for as long as I had the patience to watch it. Switching to a static wallpaper immediately resolved this for me, and it has remained stable for over 24 hours. I cannot tell you anything about the kernel bleed, but can attest to idleassetid being one of the culprits.

There are threads on this issue (macOS continuously downloading screensavers) dating back to 2024. The files you show above as well as the data used point to the issue.

I don't know why people are trying to suggest completely crazy things like "you shouldn't use your local storage", but I'm guessing it's a brand loyalty thing not rooted in any real data or a background in comp-sci. It's clearly a bug, but reporting this kind of thing is really hard if you're not a developer. Don't waste hours of your day uninstalling things and running system checkers if you see hundreds of GB of stuff in the folder idleassetsd saves things to. It's clearly an Apple issue - that process is stuck in a loop or is so poorly designed that it's not aware of current disk space usage and is on a mission to download every screensaver 4K HD 240 FPS video Apple has available, even if that's like 20TB or something. :)

Imagine if you lived somewhere where you get billed for bandwidth usage, or you're rural and on satellite, fixed wireless or DSL? And then you come on here and people point at your printer's kernel extension or something? Crazy!

In my case it kept downloading after switching to static assets for the screensaver, so I just blocked idleassetsd at the firewall level until I see someone mentioning this as being fixed.

Here's something else interesting:

On May 7th, between 17:54 and 18:30 EDT, these 54 files were updated, they are 4K 240 fps movies, all dynamic wallpapers. I also took a peek at my Internet download usage. For that day, downloads spiked at 79GB compared to the days before and after, so I'm thinking that this 30 GB or so was downloaded then. Note that prior to that, only 3 files were there, then, two around noon on May 7th, then these 54.

Can anyone confirm they received a bunch of files at around that time? You can check in:

MacIntosh HD/Library/Application Support/com.apple.idleassetsd/Customer/4KSDR240FPS. They should have a bunch of .mov files with the same date, about the same time.

I just want to see if it was something triggered internally by "idleassetsd", or something that Apple did. If the latter, I wish they would own up to it so that we can stop chasing ghosts. Even then, I think I'd have a problem if Apple dumped a bunch of non-essential files onto my machine without notifying me.

I’ve been running into this the last week too:

  - MacBook Air M2 16/512

  - MacOS Sequoia 15.5 (24F74)

  - No clear activity in Activity Monitor or Finder file/folder size

  - I do have the fancy Screen savers turned on (but I don’t think it’s related yet).

Some suggestions of activities that could be related: 

• com.apple.knowledgeconstructiond

     - learning for Spotlight/Siri

• com.apple.duetexpertd -

     - on device predictions for apps or Siri Suggestions

Each time I have rebooted the space is cleared, but then starts getting chewed up.

Possible fix:

I’ve now turned off Siri in Settings (but I've left Apple Intelligence ON) -> Apple Intelligence & Siri.

    - That has stopped rapid HD consumption so far.

   Will test this for a few hours to see if it sticks.

There is definitively something going on, that is causing the kernel task to spike and for Space to Grow / Shrink

I second the suggestion by @ Luis S to run the Etrecheck application

To skip the Q&A session, just download the Application Etrecheck directly from the Developer. 

It’s a diagnostic tool that doesn’t change your computer at all. It gives you a clear and easy-to-read list of both your hardware and software. 

You can get it for free or pay for extra features. And don’t worry, the report won’t reveal any personal information. 

Once you’re done, just copy and paste the full report using the Additional Text Icon.

I've had this since 15.4.1 on only one of my Macs: MBA M3 base config.

I normally have 150-160 GB free, but three times since installing 15.4.1 (twice since 15.5) disk space has become so low that TM backups failed.

Disk usage in my home directory is normal, so the space is being consumed elsewhere: 'System Data'.

I filed FB17734223 w/ sysdiagnose.

caught it in the act of maxing out BB connection w/ downloads; fs_usage give _many_ lines of the form

17:35:33.114212 WrData[AT1] D=0x01652af2 B=0xa000 /dev/disk3s5 private/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/T/com.apple.idleassetsd/CFNetworkDownload_dmmPNr.tmp 0.000648 W idleassetsd.3017367

17:35:33.115852 WrData[AT1] D=0x0167cb57 B=0xf6000 /dev/disk3s5 private/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/T/com.apple.idleassetsd/CFNetworkDownload_dmmPNr.tmp 0.000245 W idleassetsd.3017367

and performed a sysdiagnose

disk will shortly be full...

So disk space has been stable for a couple hours after disabling Siri on MacOS. I turned Siri back on, and it has remained stable since. Will continue to monitor.

The fileproviderdaemon processes are mentioned in the report.

My suspicion is that this could be due to your linking your OneDrive storage to your mac.

Also, from this:

Kernel Extensions:
  /Library/Extensions
    [Not Loaded] hp_fax_io.kext - com.hp.kext.hp-fax-io (5.28.0 - SDK 10.12)
    [Not Loaded] hp_io_enabler_compound.kext - com.hp.kext.io.enabler.compound (3.4.0)
    [Not Loaded] JabraUSB.kext - com.jabra.usbdevice (1.0.8 - SDK 10.15)
    [Not Loaded] SXUPTP.kext - com.silex.driver.sxuptp (1.10.10 - SDK 10.8)

These things make it look like you upgraded year after year and across multiple macs.

It is recommended, especially when moving to a new mac architecture like Apple Silicon, to migrate ONLY the user accounts, thus leaving things like this old cruft behind.

Try starting your mac in Safe Mode, and deleting these unwanted kernel extensions.

As you go about it, you could let your mac run for a while in Safe Mode - that is something that one does not usually do, but now the M series macs are so fast that you barely notice they are on Safe Mode.

If you don't see the space being consumed while in Safe Mode it will reinforce the notion that some third party software is causing this. Note that "kernel task" is a process by which the OS serves requests, so just noticing that it is using a lot of CPU, memory or disk space does not unfortunately tell us much as to why or who.

The Kernel Task issue is directly related to the lack of useable Free Space on the drive

Yes, restarting the computer have cleared some cache files and therefore created some additional Free Space

Unfortunately, the more the computer was used, the more cache files were created. This would be unavoidable.

It seems your computer requirements may have grown since the purchase of this machine

They may have grown beyond the abilities and configuration of this machine

Not sure what the longer term solution would be except to maybe consider a computer with a larger Internal Drive on you next purchase ?

From the supplied Etrecheck Report

Low disk space - This computer is running low on free hard drive space.

Hardware Information:  MacBook Pro (13-inch, M2, 2022)

disk0 - APPLE SSD AP0256Z 251.00 GB (Solid State - TRIM: Yes) 

Used: 173.30 GB

Size: 245.11 GB

Free: 49.05 GB

Available: 65.22 GB

Sigh.. back again but this time with com.apple.idleassetsd taking up all available storage space. A reboot clears it, but the system runs away until that happens.

Was able to grab a screen shot using Daisy Disk showing the rouge issue.

Submitted feedback to Apple via their MacOS Feedback app: ID# FB18363531 incase anyone want to reference my feedback in theirs.

Now 256GB free. "System Data" has disappeared completely! Something is definitely happening in 15.5.