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

Hi everyone,

I recently updated to macOS Sequoia 15.4.1 (24E263) and started experiencing a serious issue with my disk space. After a restart, I typically have around 80–90 GB of free space — but that space rapidly disappears until only about 980 MB remains. At that point, it stops decreasing, but it's still unusable.

Using Activity Monitor, I noticed that:

First, the idleassetsd process was writing an enormous amount of data.
After restarting (which seemed to temporarily fix it), the issue returned — this time with kernel_task as the culprit.

I tried switching to a static desktop background after reading that idleassetsd might be related to dynamic wallpapers, but it didn't help with the kernel task writing issue. Restarts don't help anymore either.

I’ve searched the forums and found some posts about similar symptoms, but nothing definitive — just a lot of speculation. Has anyone experienced the same thing or found a reliable solution? This is becoming quite frustrating, as my available disk space keeps "melting" away without any apparent reason.

Any help or insight would be greatly appreciated!

Thanks in advance.

MacBook Pro 13″, macOS 15.4

Posted on Apr 23, 2025 1:14 AM

Top-ranking reply

Liteyear

Level 1

35 points

Posted on May 28, 2025 9:55 PM

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:

"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".
The number associated with "System Data" is bizarre. Take it with a big grain of salt.
Storage management is just too complicated to leave to general hygiene or even the "Storage" view in System Preferences. Don't delay - get GrandPerspective.
VSCode extensions are the wild west - loose cannons that shoot at will.

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31 replies

BDAqua

Level 10

250,259 points

May 28, 2025 10:11 PM in response to Liteyear

Whooot, great work!

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