Running out of storage - system data is huge after upgrade to macOS Tahoe 26.2

Run the third party app EtreCheck and post the complete report here so we can examine it for clues.

How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community

FYI, deleting the cache files is not going to help since they will be rebuilt as soon as you use the associated app. Any increase is just temporary.

you appear to have several different file sharing and file serving services installed.

File providers:

[Loaded] Dropbox - /Applications/Dropbox.app

[Loaded] OneDrive File Provider - /Applications/OneDrive.app

Share services:

[Loaded] Secure Client - /Applications/AnyConnect.app

[Loaded] Dropbox Transfer - /Applications/Dropbox.app

[Loaded] OneNote - /Applications/Microsoft OneNote.app

Next on the list of resource hogs is Non-native File Sync-ers. Dropbox, BackBlaze, OneDrive, Carbonate, or Google drive and others are in this category. Since they were ported from that other OS environment, they IGNORE the Mac File System Event Store (that could tell them EXACTLY what folders have changed recently).

Onstead, they do a a Brute-force read of all your files, and all the files stored on their drive on the Internet. This punishes the ability to get any data (including speed test data) through their enormous and frivolous file reading and re-reading.

They are also 'on the phone' checking and re-checking the synced file stored on the internet. Between constant scanning and constant Internet access, this uses a LOT of resources -- far more than Apple-native File-Syncers like iCloud. Running File-Syncers when not actually needed still consumes a lot of computer resources. You should NOT be launching these at Startup, but instead launch only when needed, and quit when Sync-ing is complete.

Backup-to-the-Web Utilities are also in this category. Your backup should be on a local drive, not on the web. If you question this, just ask.

NB>> if you allow this to launch at LOGIN, they will punish BOTH your file system and your internet performance.

settings > general > Open at login ...

sleet and REMOVE each of the items found here.

(Then they will launch their background tasks later, when you invoke them, and not otherwise)

if you have Time Machine enabled for automatic backups, it is preparing to make a new backup, including any changes induced by your upgrade.

If you have not connected your external drive recently, snapshots of the lists of files to be backed up are being saved on the boot drive.

if this is the case for you, connect your external Time Machine drive and let it make a "real" backup to the external drive, and it will clear those snapshots when competed.

Reducing System/Volume/Data is a common question. 

1 -  System data taking too much in MacOS Sono… - Apple Community

2 - Time Machine Local Snapshot won't delete - Apple Community

3 - Over 60% storage blocked by System Data - Apple Community

How to free up ‘System Data’ and other storage on your Mac from a fellow colleague  @ neuroanatomist

Use another application to see where space is being used  Storeograph  on the Apple Apps Store 

View APFS snapshots in Disk Utility on Mac

Suggest getting an External SSD Drive and start moving your Pictures, Videos, Music and any other large files you have control over, OFF the Internal drive and Onto the External

Understanding iCloud Drive from a well written User Tip from @ Richard.Taylor

There are  two effective ways to remedy this issue:

1. Quick Fix Actions:

 For Apple Silicon computers, use Disk Utility to erase a Mac.

Always make a Time Machine backup before proceeding.

 Migrate only the user account, not the entire system.

 Reinstall only the necessary applications from the Apple App Store or directly from the developers.

2 - Generally

When the user discovers this issue, in this specific case, computer’s internal drive capacity is small, such 256 GB

Unfortunately, the user’s storage needs may have increased since the computer was purchased.

To future-proof the computer, consider spending extra money upfront on a larger drive capacity and adding more unified RAM.

Note - On Apple Silicon and newer computers. The SSD Drive and the Unified RAM are Soldered to the Logicboard and can not be upgraded.

More on your drive and Grant's comments:

The "File System" time of 11 seconds suggests the drive is healthy, but a write speed of 365 MB/sec is glacial and only slightly faster than the best mechanical hard drives. I've viewed lots of such reports, and the SSD in M1/M2 Mac laptops should show both Writes and Reads doing around 3000 MB/sec or more.

When you get free space under control, rerun EtreCheck again to see if these speeds increase.

While away from your TM drive, you can use Disk Utility (in Applications > Utilities) to review snapshots and their size. On my Macbook Pro, It never shows more than two when the TM drive remains attached:

Below the list of snapshots is a "delete" button (not shown).

As for RAM, yes *GB is tight, but this offers why you SWAP was high a the time of testing:

System Software:

macOS Tahoe 26.2 (25C56)

Installed 2026-01-30

Time since boot: About 8 days ⬅️

Assuming you cannot replace this *GB RAM Mac soon, restarting every two days or so resets the RAM and zeros SWAP, improving performance.

Running with very little free space is like playing catch with a live grenade. It's all fine...until it isn't.

System Data is stuff that Spotlight hasn't categorized. Have you tried rebuilding your Spotlight index?

Rebuild the Spotlight index on your Mac - Apple Support

2025-12-17 Xcode (16.2) - App Store

It is possible Xcode 15.2 is part of the lack of Free Space

This may dovetail into your original posting regarding the " Developer " category

It does report this application is about 12.14 GB in size

To regain some Free Space

You may consider removing it

Then, change your setting in Apple Apps Store

You are permitted to Install Xcode onto to an External Drive

Refer to 3rd image regarding Apple Apps Store >> Setting

Settings > General > Internet Sharing ... is ON

You are actively Sharing (read: making available for others to use) your Internet connection to other local devices.

Unless you are actively using this feature at this moment, it should generally be turned OFF.

Unsigned files:

you have several normally-signed apps and extensions added that, if they were completely up to date and valid, should be fully signed.

After really comparing to its database of known unsigned old versions, Etrecheck has flagged them as likely MALWARE:

Unsigned Files:

Launchd: /Library/LaunchDaemons/com.microsoft.teams.TeamsUpdaterDaemon.plist

Executable: /Applications/Microsoft Teams classic.app/Contents/TeamsUpdaterDaemon.xpc/Contents/MacOS/TeamsUpdaterDaemon

Details: Restrictive config permissions - possibly malware

Running app: /Library/DropboxHelperTools/Dropbox_u501/dbkextd

Details: Domain name invalid - possibly malware

Running app: /Applications/XAMPP/xamppfiles/manager-osx.app/Contents/MacOS/installbuilder.sh

Details: Gatekeeper bypass

These are clearly NOT the correct versions, and they may be malware. These versions of these apps should be deleted. At a minimum they should be updated. Best Practice would be to completely remove and re-install up-to-date versions.

Review this for some help:

https://discussions.apple.com/thread/256239409?sortBy=newest_first

On closer examination, you appear to have at least portions of Fortinet AND Cisco AnyConnect VPNs loaded.

The correct number of VPNs is Zero, unless you are connecting for presence on an Institution's network, and in that case the institution will manage that VPN for you.

There is so much stuff running an background AND your boot drive is so full, its write speed has dropped to levels that are astonishingly slow. Typically, write speeds are slightly FASTER than read speeds because of write buffering. But yours are:

Write speed: 356 MB/s

  Read speed: 1315 MB/s

--------

Virtual Memory Information:

Physical RAM: 8 GB

Free RAM: 62 MB

Used RAM: 7.12 GB

Cached files: 835 MB

Available RAM: 896 MB

Swap Used: 8.03 GB this is how much space was needed, but NOT available, to run everything you have loaded at the time of that report. The excess has spilled out to a file on the boot drive. Your boot drive is already way to full and therefore way too slow.

Your 8 GB physical RAM memory is too small to be running MacOS 26 Tahoe and multiple Applications at the same time. Apple no longer sells computers with only 8GB RAM. To use this computer effectively, you should QUIT each app before launching the next one.

You should SERIOUSLY consider upgrading to a computer with more RAM memory.

etresoft wrote:

wallywallllter wrote:

So Xcode really isn't that important for me and could easily install it onto an external hard drive.

Yes and no. You can install Xcode, and any 3rd party apps, on an external drive. But that won't help. Xcode uses a tremendous amount of additional storage on your startup volume. You can't change this. On my 1 TB machine, this extra Xcode data takes 300 GB, which is larger than your entire hard drive.

Thanks for that additional and important info 👍

wallywallllter wrote:

I did a Time Machine backup today and this didn't resolve anything.

To my surprise, the "applications" part is now only half the size, but the "System Data" part is now 134GB (about 100GB prior to the time machine backup).

This is insane. I've always been very happy with Mac, but this seems like a serious bug.

I have several Macs working well, one has 66 GB System data and the other 94 GB System Data. Another has 20 GB System Data. On my Macs with the larger System Data totals, I believe System Data includes a lot of image files in various Photos libraries (that are in addition to the primary Photos Library) as well as other files (including some non-Apple email files and attachments) that I had expected Apple would categorize into other more logical ways but for some reason it doesn't.

Because the Apple Storage sorting and binning is inconsistent, I don't think it can be relied on. A better sense can be had from utilities like DaisyDisk.

I can't imagine being able to function comfortably with just 256 GB total storage. This will be a recurring problem and will never go away until you move significant amounts of files and folders to external drives. But that defeats the motivation for such a slim and nimble laptop like the Macbook Air, now you have to tether external drives to it just to work on things. And you have to pay for those external drives (plus additional drives to back them up), just as paying more when the original purchase was made would have provided you with workable disk space.

I think 8 GB is also inadequate RAM and maybe not after a fresh reboot, but fairly soon after it has been running it will have to start paging to disk when memory is consumed. Putting more pressure on disk space. Your disk speeds of 1100 and 1500 MB/s are very slow still for an SSD, my 2019 laptop gets 3000 MB/s. So something is still wrong or the lack of space is just throttling your Mac back.

tbirdvet wrote:

Review this for some help:

https://discussions.apple.com/thread/256239409?sortBy=newest_first

👍

🦉-53

<<. etrecheck report >>

Your 256 GB drive is very small by todays standards. You may need to consider always using an external drive as well.

you need not use a huge spinning magnetic desktop-style drive with its own power supply. Here are some examples of smaller drives for laptops: